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Punjab State Board PSEB 10th Class Hindi Book Solutions Chapter 1 दोहावली Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Hindi Chapter 1 दोहावली

Hindi Guide for Class 10 PSEB दोहावली Textbook Questions and Answers

(क) विषय-बोध

I. निम्नलिखित प्रश्नों के उत्तर एक या दो पंक्तियों में दीजिए

प्रश्न 1.
तुलसीदास जी के अनुसार राम जी के निर्मल यश का गान करने से कौन-से चार फल मिलते हैं ?
उत्तर:
तुलसीदास जी के अनुसार राम जी के निर्मल यश का गान करने से धर्म, अर्थ, काम और मोक्ष नामक चार फल मिलते हैं।

प्रश्न 2.
मन के भीतर और बाहर उजाला करने के लिए तुलसी कौन-सा दीपक हृदय में रखने की बात करते हैं?
उत्तर:
तुलसी हृदय में श्रीराम नाम रूपी मणियों के दीपक को रखने की बात करते हैं।

प्रश्न 3.
संत किस की भाँति नीर-क्षीर विवेक करते हैं?
उत्तर:
संत हंस की भाँति नीर-क्षीर विवेक करते हैं।

प्रश्न 4.
तुलसीदास के अनुसार भव सागर को कैसे पार किया जा सकता है?
उत्तर:
तुलसीदास के अनुसार श्रीराम से स्नेह, सांसारिक प्राणियों से समता तथा राग, रोष, दोष, दुःख आदि का त्याग करने से भव सागर को पार किया जा सकता है।

प्रश्न 5.
जो व्यक्ति दूसरों के सुख और समृद्धि को देखकर ईर्ष्या से जलता है, उसे भाग्य में क्या मिलता है?
उत्तर:
जो व्यक्ति दूसरों की सुख-समृद्धि से ईर्ष्या में जलता है उसे अपने जीवन में कभी सुख की प्राप्ति नहीं होती।

प्रश्न 6.
रामभक्ति के लिए गोस्वामी तुलसीदास किसकी आवश्यकता बतलाते हैं?
उत्तर:
गोस्वामी तुलसीदास रामभक्त के लिए ईश्वर की भक्ति, नीर-क्षीर विवेकी होने और परम आस्तिकता के भावों की आवश्यकता बतलाते हैं। रामभक्ति के लिए संत समागम और हृदय की पवित्रता आवश्यक है।

II. निम्नलिखित पद्यांशों की सप्रसंग व्याख्या कीजिए

(1) प्रभु तरुतर कपि डार पर, ते किए आपु समान।
तुलसी कहुँ न राम से, साहिब सील निधान।
(2) सचिव, वैद, गुरु तीनि जो, प्रिय बोलहिं भयु आस।
राज, धर्म, तन तीनि कर, होइ बेगिही नास।
उत्तर:
(1) कवि कहता है कि प्रभु श्री राम जी तो वृक्षों के नीचे और बंदर वृक्षों की डालियों पर रहते थे, परंतु ऐसे बंदरों को भी उन्होंने अपने समान बना लिया। तुलसीदास जी कहते हैं कि श्रीरामजी जैसे शीलनिधान स्वामी अन्य किसी स्थान पर कहीं भी नहीं हैं।

(2) कवि कहता है कि स्वामी से तो वह सेवक बड़ा होता है जो अपने धर्म के पालन को करने में निपुण होता है। इसीलिए स्वामी श्रीराम तो सागर पर पुल बंधने के बाद ही समुद्र पार कर सके परंतु उनका सेवक हनुमान तो बिना पुल के ही समुद्र लांघ गया था।

(ख) भाषा-बोध

निम्नलिखित शब्दों के विपरीत शब्द बनाएं-

शब्द = विपरीत शब्द
संपत्ति = ——–
सेवक = ——–
भलाई = ——–
लाभ = ———-
उत्तर:
शब्द = विपरीत शब्द
संपत्ति = विपत्ति।
सेवक = स्वामी।
भलाई = बुराई।
लाभ = हानि।

2. निम्नलिखित शब्दों की भाववाचक संज्ञा बनाएं-

दास = ——–
निज = ——–
गुरु = ——–
जड़। = ———
उत्तर:
शब्द . विपरीत शब्द
दास = दासता।
निज = निजता।
गुरु = गुरुत्व।
जड़ = जड़ता।

3. निम्नलिखित के विशेषण बनाएँ-

धर्म = ——–
मन = ———
भय = ———
दोष। = ———
उत्तर:
शब्द – विशेषण शब्द
धर्म = धार्मिक।
मन = मानसिक।
भय = भयनक।
दोष = दोषी।

(ग) पाठ्येतर सक्रियता

प्रश्न 1.
अपने विद्यालय के पुस्तकालय से गोस्वामी तुलसीदास से संबंधित पुस्तकों से उनके जीवन की अन्य घटनाओं के बारे में जानकारी प्राप्त करें।
उत्तर:
(विद्यार्थी स्वयं करें।)

प्रश्न 2.
तुलसीदास द्वारा रचित दोहों की ऑडियो या वीडियो सी०डी० लेकर अथवा इंटरनेट से इन दोहों को सुनकर आनंद लें और स्वयं भी इन को याद कर लय में गाने का अभ्यास करें।
उत्तर:
(विद्यार्थी स्वयं करें।)

प्रश्न 3.
इंटरनेट के माध्यम से राष्ट्रीय दूरदर्शन पर दिखाए ‘तुलसीदास’ के जीवन पर आधारित सीरियल को ग्रीष्म अवकाश में देखें। उत्तर:
(विद्यार्थी स्वयं करें।)

(घ) ज्ञान विस्तार

रामभक्त गोस्वामी तुलसीदास जी द्वारा रचित हनुमान चालीसा का प्रथम दोहा ‘श्री गुरु चरन सरोज रज’ कवि की हनुमान जी के प्रति श्रद्धा-भक्ति का प्रतीक है। हनुमान जी को केसरी नंदन तथा अंजनि पुत्र भी कहते हैं। केसरी इनके पिता तथा अंजना माता थी। लंका में सीता का समाचार लाते समय ये एक ही छलांग में समुद्र लांघ गए थे और जब इनकी पूंछ में आग लगा दी गई थी तब इन्होंने रावण की सारी लंका ही जला दी थी। लक्ष्मण मूर्छा के समय ये ही लंका से सुषेण वैद्य को तथा उसके कहने पर संजीवनी बूटी को लाए थे। इन्होंने ही सुग्रीव की श्रीराम जी के साथ मित्रता करवा कर उसे उसका राज्य दिलवाया था। इस प्रकार हनुमान महाबली तथा श्री राम जी के अनन्य सेवक माने जाते हैं।

PSEB 10th Class Hindi Guide दोहावली Important Questions and Answers

प्रश्न 1.
कवि के अनुसार श्रीराम जी जैसा शीलनिधान अन्य कोई क्यों नहीं है?
उत्तर:
श्रीराम जैसा शील निधान अन्य कोई भी नहीं था क्योंकि श्रीराम ने वानरों को भी पूरा सम्मान दिया था।

प्रश्न 2.
बिना हरि कृपा के क्या प्राप्त नहीं हो सकता?
उत्तर:
हरि कृपा के बिना संत-समागम नहीं प्राप्त हो सकता।

प्रश्न 3.
ईर्ष्यालु व्यक्ति की क्या दशा होती है?
उत्तर:
ईर्ष्यालु व्यक्ति सदा ईर्ष्या की आग में जलता रहता है तथा उसका कभी भी भला नहीं होता है।

प्रश्न 4.
भगवान् से भक्त को बड़ा बताने के लिए तुलसीदास ने कौन-सा उदाहरण दिया है?
उत्तर:
श्रीराम को लंका जाने के लिए समुद्र पर पुल बंधवा कर जाना पड़ा जबकि उनके भक्त हनुमान छलांग लगा कर ही समुद्र पार कर लंका पहुँच गए थे।

प्रश्न 5.
चापलूस दरबारियों से क्या हानि होती है?
उत्तर:
चापलूस दरबारी सदा राजा की हाँ में हाँ मिलाते हैं, उसकी आलोचना कभी भूलकर भी नहीं करते जिससे राजा अपने राज्य, धर्म और अपने शरीर का भी नाश झूठे अभिमान के कारण कर देता है।

प्रश्न 6.
कैसी भक्ति के बिना श्रीराम अपने भक्तों पर कृपा नहीं करते?
उत्तर:
जिस भक्ति में श्रीराम के प्रति विश्वास नहीं होता उन भक्तों पर श्रीराम कृपा नहीं करते।

(क) एक पंक्ति में उत्तरात्मक प्रश्न

प्रश्न 1.
तुलसी ने हृदय में कैसे दीपक को रखने की बात कही है?
उत्तर:
तुलसी ने हृदय में श्रीराम नाम रूपी मणियों के दीपक के रखने की बात कही है।

प्रश्न 2.
राम की कृपा के बिना स्वप्न में भी क्या नहीं मिलता ?
उत्तर:
राम की कृपा के बिना स्वप्न में भी जीवन में चैन नहीं मिलता।

प्रश्न 3.
श्रीराम ने सागर कैसे पार किया था ?
उत्तर:
श्रीराम ने सागर पर बने पुल से सागर पार किया था।

प्रश्न 4.
हंस की भांति नीर-क्षीर विवेक कौन करते हैं?
उत्तर:
संत हंस की भांति नीर-क्षीर विवेक करते हैं।

(ख) निम्नलिखित प्रश्नों के उत्तर एक सही विकल्प चुनकर लिखें

प्रश्न 1.
‘श्री गुरु चरन सरोज रज’ में सरोज है
(क) सरोवर
(ख) कमल
(ग) सरिता
(घ) धूल।
उत्तर:
(ख) कमल

प्रश्न 2.
‘निज मन मुकुरु सुधारि’ में मुकुरु है
(क) मुकरना
(ख) मौसम
(ग) शीशा
(घ) सुधरना।
उत्तर:
(ग) शीशा

प्रश्न 3.
भगवान् पर क्या किए बिना भक्ति नहीं हो सकती
(क) दया
(ख) विश्वास
(ग) प्रार्थना
(घ) समझौता।
उत्तर:
(ख) विश्वास

प्रश्न 4.
‘दोहावली’ किसकी रचना है
(क) तुलसीदास
(ख) वृन्द
(ग) बिहारी
(घ) रहीम।
उत्तर:
(क) तुलसीदास

(ग) एक शब्द/हाँ या नहीं/सही-गलत/रिक्त स्थानों की पूर्ति के प्रश्न

प्रश्न 1.
संत किस की भाँति नीर-क्षीर विवेक करते हैं? (एक शब्द में उत्तर दीजिए)
उत्तर:
हँस

प्रश्न 2.
राम जी का निर्मल यशगान करने से चार फल मिलते हैं। (हाँ या नहीं में उत्तर लिखें)
उत्तर:
हाँ

प्रश्न 3.
अपने धर्म में निपुण सेवक साहब से बड़ा नहीं होता। (सही या गलत लिख कर उत्तर दें)
उत्तर:
गलत

प्रश्न 4.
तुलसीदास राम के भक्त थे। (सही या गलत लिख कर उत्तर दें)
उत्तर:
सही

प्रश्न 5.
बरनऊं रघुबर ……. जसु।
उत्तर:
बिमल

प्रश्न 6.
गिरिजा संत ……….. सम।
उत्तर:
समागम

प्रश्न 7.
राज, धर्म, तन तीनि कर, होइ ……. नास।
उत्तर:
बेगिही।

दोहावली दोहों की सप्रसंग व्याख्या

1. श्री गुरु चरन सरोज रज, निज मन मुकुरु सुधारि।
बरनऊँ रघुबर विमल जसु, जो दायकु फल चारि॥

शब्दार्थ:
चरन = पैर। सरोज = कमल। रज = धूल। मकरु = दर्पण। बरनऊँ = वर्णन करूँ। विमल = निर्मल, उज्ज्वल। जसु = यश। दायकु = देने वाले। फल चारि = चार फल-धर्म, अर्थ, काम और मोक्ष।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है। यह दोहा हनुमान चालीसा का प्रारंभिक दोहा है। इस दोहे में गुरु वंदना के बाद श्रीराम के पवित्र चरित्र के गुणगान करने की कवि ने कामना की है।

व्याख्या:
कवि कहता है कि मैं श्री गुरु महाराज के चरण कमलों की धूल से अपने मनरूपी दर्पण को स्वच्छ और पवित्र करके श्री रघुवीर रामजी के निर्मल पवित्र यश का वर्णन करता हूँ, जो चारों फलों धर्म, अर्थ, काम और मोक्ष को देने वाला है।

विशेष:

1. कवि अपने सद्गुरु की कृपा प्राप्त कर श्रीराम के उज्ज्वल चरित्र का गुणगान करने की कामना कर रहा है।
2. भाषा ब्रज मिश्रित अवधी, दोहा छंद, अनुप्रास, उपमा तथा रूपक अलंकार हैं।

2. राम नाम मनी दीप धरु, जीह देहरी द्वार।
तुलसी भीतर बाहरु हुँ, जौ चाहसि उजियार॥

शब्दार्थ:
मनी = मणियाँ। दीप = दीपक। जीह = जीभ । देहरी = दहलीज। चाहसि = चाहता है। उजियार = उजाला।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है, जिसमें कवि ने श्रीराम के नाम स्मरण की महिमा का वर्णन किया है।

व्याख्या:
तुलसीदास जी कहते हैं कि हे मानव, तू राम नाम रूपी मणि-दीपक को मुखरूपी द्वार की जीभरूपी दहलीज पर रख। यदि तू भीतर और बाहर दोनों ओर उजाला चाहता है। भाव यह है कि राम नाम रूपी मणियों से बने दीपक को हृदय में धारण करने से अज्ञान रूपी अंधेरा नष्ट हो जाता है तथा ज्ञान रूपी उजाला हो जाता है।

विशेष:

1. राम नाम के स्मरण से समस्त दोषों का नाश हो जाता है तथा हृदय के बाहर और भीतर उजाला हो जाता है।
2. ब्रज भाषा में अवधी के शब्दों का मिश्रण है। दोहा छंद, रूपक अलंकार है।

3. जड़ चेतन गुन दोषभय, बिस्व कीन्ह करतार।
संत हंस गुन गहहिं पय, परिहरि बारि विकार॥

शब्दार्थ:
जड़ = निर्जीव। चेतन = सजीव। बिस्व = संसार। करतार = ईश्वर, परमात्मा। गहहिं = लेकर। पय = दूध। परिहरि = छोड़कर। बारि = पानी। विकार = बुराई।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ में से लिया गया है, जिसमें कवि ने संतों की विशेषता का वर्णन किया है।

व्याख्या:
तुलसीदास कहते हैं कि परमात्मा ने इस जड़-चेतन संसार को गुण और दोष से युक्त बनाया है, परंतु संत हँसों के समान नीर-क्षीर विवेकी होने के कारण दोष रूपी जल को त्याग कर गुण रूपी दूध को ग्रहण करते हैं।

विशेष:

1. संत सदा सद्गुणों से युक्त होते हैं। वे विकारों से रहित होते हैं।
2. अवधी भाषा, दोहा छंद, अनुप्रास तथा रूपक अलंकार का प्रयोग सराहनीय है।

4. प्रभु तरुतर कपि डार पर, ते किए आपु समान।
तुलसी कहुँ न राम से, साहिब सील निधान। 

शब्दार्थ:
तरुतर = वृक्ष के नीचे। कपि = वानर। आयु = अपने।

प्रसंग:
प्रस्तुत दोहा तुलसीदास के द्वारा रचित ‘दोहावली’ से लिया गया है। इस दोहे में कवि ने श्रीराम द्वारा वानरों को दिए गए सम्मान का वर्णन किया है।

व्याख्या:
कवि कहता है कि प्रभु श्री राम जी तो वृक्षों के नीचे और बंदर वृक्षों की डालियों पर रहते थे, परंतु ऐसे बंदरों को भी उन्होंने अपने समान बना लिया। तुलसीदास जी कहते हैं कि श्रीरामजी जैसे शीलनिधान स्वामी अन्य किसी स्थान पर कहीं भी नहीं हैं।

विशेष:

1. श्रीराम की सबके प्रति समतावादी दृष्टि का उल्लेख किया गया है। वे कोई भी भेदभाव न करते हुए सबको अपने समान बना लेते थे।
2. अवधी भाषा, दोहा छंद, अनुप्रास अलंकार है।

5. तुलसी ममता राम सो, समता सब संसार।
राग न रोष न दोष दुःख, दास भए भव पार॥

शब्दार्थ:
ममता = स्नेह, प्रेम। समता = बराबर। राग = प्रेम। रोष = क्रोध। भव = संसार।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है। इस दोहे में कवि ने श्रीराम के प्रति आस्था रखने तथा सांसारिक प्राणियों से समभाव रखने की प्रेरणा दी है।

व्याख्या:
तुलसीदास जी कहते हैं कि श्रीराम से ममता रखो तथा संसार के प्राणियों के प्रति समभाव रखो, इससे मनुष्य राग, रोष, दोष, दुःख से मुक्त हो जाता है तथा श्रीराम का दास होने के कारण इस संसार रूपी सागर से पार हो जाता है।

विशेष:

1. सांसारिक माया-मोह के बंधनों से मुक्त होकर भव-सागर पार करने के लिए श्रीराम के प्रति ममता होनी आवश्यक है।
2. अवधी भाषा, दोहा छंद, अनुप्रास तथा रूपक अलंकार हैं।

6. गिरिजा संत समागम सम, न लाभ कछु आन।
बिनु हरि कृपा न होइ सो, गावहिं वेद पुरान॥

शब्दार्थ:
गिरिजा = पार्वती। सम = समान। आन = अन्य, दूसरा।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है। इस दोहे में कवि ने संत-समागम की महिमा का वर्णन किया है।_

व्याख्या:
कवि कहता है कि शिव जी पार्वती को संतों के सम्मेलन की महिमा का वर्णन करते हुए कहते हैं कि हे पार्वती, संतों के साथ मिल बैठकर उनके विचार सुनने के समान संसार में अन्य कुछ भी लाभकारी नहीं है तथा संत-समागम भी श्रीराम की कृपा के बिना नहीं मिलता। ऐसा वेद-पुराणों में भी कहा गया है।

विशेष:

1. संत-समागम प्रभु कृपा से प्राप्त होता है तथा इसके समान लाभदायक संसार में और कुछ भी नहीं है।
2. भाषा अवधी, दोहा छंद तथा अनुप्रास अलंकार हैं।

7. पर सुख संपत्ति देखि सुनि, जरहिं जे जड़ बिनु आगि।
तुलसी तिन के भाग ते, चलै भलाई भागि॥

शब्दार्थ:
पर = पराया, दूसरे का। जरहिं = जलना, ईर्ष्या करना। जड़ = मूर्ख भाग = भाग्य। भागि = भाग जाना, चले जाना।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है, जिसमें कवि ने ईर्ष्यालु व्यक्ति की दुर्दशा का वर्णन किया है।

व्याख्या:
गोस्वामी तुलसी दास कहते हैं कि दूसरे के सुख और संपत्ति को देख-सुन कर जो मूर्ख बिना आग के ही जलते रहते हैं, उन लोगों के भाग्य से भलाई स्वयं ही भाग जाती है। भाव यह है कि दूसरों की उन्नति को देखकर ईर्ष्या करने वाले व्यक्ति का कभी भी भला नहीं होता है।

विशेष:

1. ईर्ष्यालु व्यक्ति का कभी भी भला नहीं होता है और न ही सुख की प्राप्ति होती है।
2. भाषा अवधी-ब्रज का मिश्रण, दोहा छंद, अनुप्रास अलंकार हैं।

8. सचिव वैद गुरु तीनि जो, प्रिय बोलहिं भयु आस।
राज, धर्म, तन तीनि कर, होइ बेगिही नास॥

शब्दार्थ:
सचिव = मंत्री। वैद = वैद्य। प्रिय बोलहिं = मीठा बोलना, मुँह देखी बोलना। भयु = डर से। तीनि = तीनों। बेगिही = शीघ्र ही। नास = नाश, विनाश।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है, जिसमें कवि ने राजा के भय से उसकी हाँ में हाँ मिलाने वाले चापलूसों के परिणाम का वर्णन किया है।

व्याख्या:
कवि कहता है कि यदि किसी राजा का मंत्री, वैद्य और गुरु–ये तीनों राज-भय से अथवा किसी लोभलालच से उसकी बात जैसी है वैसी ही मान लेते हैं अथवा उसकी हाँ में हाँ मिलाते हैं तो उसके राज्य, धर्म और शरीर तीनों का शीघ्र ही विनाश हो जाता है।

विशेष:

1. तुलसी दास का मानना है कि रावण के भय से उसके सभासद सदा उसकी हाँ में हाँ मिलाते थे, इसलिए उसका विनाश हो गया था। इसलिए ऐसे चापलूसों से बचना चाहिए।
2. भाषा अवधी और ब्रज है। दोहा छंद तथा अनुप्रास अलंकार है।

9. साहब ते सेवक बड़ो, जो निज धरम सुजान।
राम बाँध उतरै उद्धि, लांघि गए हनुमान॥

शब्दार्थ:
साहब = स्वामी। उद्धि = समुद्र। बाँध = पुल। सुजान = निपुण।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित दोहावली से लिया गया है, जिसमें कवि ने भगवान् से अधिक उनके भक्त की प्रशंसा की है।

व्याख्या:
कवि कहता है कि स्वामी से तो वह सेवक बड़ा होता है जो अपने धर्म के पालन को करने में निपुण होता है। इसीलिए स्वामी श्रीराम तो सागर पर पुल बंधने के बाद ही समुद्र पार कर सके परंतु उनका सेवक हनुमान तो बिना पुल के ही समुद्र लांघ गया था।

विशेष:

1. स्वामी की कृपा से सेवक स्वामी से भी बड़ा काम कर सकता है।
2. भाषा अवधी, ब्रज, दोहा छंद, अनुप्रास अलंकार हैं।

10. बिनु बिस्वास भगति नहिं, तेहि बिनु द्रवहिं न राम।
राम कृपा बिनु सपनेहुँ, जीवन नहिं विश्राम।

शब्दार्थ:
द्रवहिं = द्रवित होना, पिघलना, दया करना। लह = प्राप्त करना, लेना।

प्रसंग:
प्रस्तुत दोहा तुलसीदास द्वारा रचित ‘दोहावली’ से लिया गया है। इस दोहे में कवि ने अपने आराध्य पर पूर्ण विश्वास रखते हुए भक्ति करने का संदेश दिया है।

व्याख्या:
कवि कहता है कि बिना भगवान् पर विश्वास किए उनकी भक्ति नहीं हो सकती। विश्वास से रहित भक्ति से श्रीराम अपने भक्त पर दया नहीं करते और राम की कृपा के बिना स्वप्न में भी जीवन में चैन नहीं मिलता है। भाव यह है कि विश्वासपूर्वक भक्ति करने से ही परमात्मा की प्राप्ति होती है।

विशेष:

1. ईश्वर की भक्ति उस पर पूर्ण विश्वास रख कर ही करनी चाहिए तभी ईश्वर की कृपा होती है।
2. भाषा अवधी, ब्रज हैं। दोहा छंद और अनुप्रास अलंकार है।

दोहावली Summary

दोहावली  कवि परिचय।

राम-भक्त कवियों में तुलसीदास का नाम विशेष आदर से लिया जाता है। उनका जन्म सन् 1532 ई० में राजापुर, ज़िला बाँदा में हुआ था। कुछ विद्वान् उत्तर प्रदेश के एटा जिले में सोरों नामक ग्राम को उनका जन्म स्थान मानते हैं। इनके पिता का नाम आत्मा राम तथा माता का नाम हुलसी था। मूल नक्षत्र में उत्पन्न होने के कारण माता-पिता ने इन्हें त्याग दिया था। इनका बचपन दर-दर की ठोकरें खाते हुए अनेक कष्टों में बीता। बाद में बाबा नरहरिदास ने उन्हें सहारा दिया। उनके पास रहकर उन्होंने शिक्षा प्राप्त की थी। बाद में काशी के महान् विद्वान शेष सनातन से उन्होंने वेद-शास्त्रों और इतिहास-पुराण का ज्ञान प्राप्त किया। विद्वान बनकर वे वापस राजपुर लौटे थे। तब दीनबंधु पाठक ने अपनी पुत्री रत्नावली से इनका विवाह करवा दिया था। वे अपनी पत्नी रत्नावली से बहुत प्यार करते थे। एक दिन वह इनको बताए बिना अपने मायके चली गई। तुलसीदास जी को जब पता चला तो अन्धेरी रात तथा मूसलाधार वर्षा में रत्नावली के पास पहुँच गए। इस पर रत्नावली ने उन्हें फटकार सुनाई और राम के चरणों में स्नेह लगाने की प्रेरणा दी।

लाज न लागत आपको दौरे आयह साथ,
धिक धिक ऐसे प्रेम को कहां कहौ हौं, नाथ।

इस घटना से तुलसीदास का हृदय ग्लानि से भर गया। उन्होंने संसार को त्याग कर अपना सारा जीवन भगवान राम की आराधना तथा भक्तिपरक साहित्य लिखने में लगा दिया। सन् 1623 ई० में तुलसीदास जी का स्वर्गवास हुआ।

रचनाएँ-तुलसीदास के नाम से 37 पुस्तकें स्वीकार की जाती हैं। लेकिन इनमें से तुलसी के प्रामाणिक ग्रन्थ बारह ही हैं, वे हैं–रामचरितमानस, वैराग्य संदीपनी, रामललानहछू, बरवै रामायण, पार्वती मंगल, जानकी मंगल, रामाज्ञा-प्रश्न, दोहावली, कवितावली, गीतावली, कृष्ण गीतावली और विनय पत्रिका।

तुलसीदास ने अपने काव्य में राम को विष्णु का अवतार मान कर उन्हें ईश्वर पद प्रदान किया है-‘सोई दशरथ सुत हित, कौसलपति भगवान्।’ उन्होंने माना है कि राम ही धर्म का उद्धार करने वाले हैं तथा उनमें शील, शक्ति और सौंदर्य के गुण विद्यमान हैं। राम के माध्यम से कवि ने अपने काव्य में आदर्श समाज की कल्पना की है। उन्होंने राम, सीता, भरत, लक्ष्मण, कौशल्या, हनुमान आदि के द्वारा आदर्श गृहस्थ, आदर्श समाज और आदर्श राज्य की कल्पना को साकार रूप दिया है। इनकी रचनाओं का मूल रस शांत है। लेकिन स्थान-स्थान पर अन्य सभी रसों का सुंदर प्रयोग दिखाई दे जाता है। कवितावली के बालकांड में वात्सल्य रस के सुंदर उदाहरण दिए गए हैं। तुलसीदास एक श्रेष्ठ कवि और सच्चे लोकनायक हैं।

इन्होंने अपने काव्य में जीवन के विविध रूपों को प्रस्तुत किया है। इन्होंने अवधी और ब्रज भाषाओं का संदर प्रयोग किया है। इनकी अधिकांश रचनाएँ अवधी में हैं। लेकिन ‘विनय पत्रिका’ में ब्रज भाषा का प्रयोग किया गया है। इनके प्रबंध काव्य में दोहाचौपाई छंदों का प्रयोग अधिक है तो मुक्तक काव्यों में गीति शैली’ की प्रधानता है। इन्होंने आवश्यकतानुसार उर्दू, फ़ारसी, बुंदेली, भोजपुरी आदि शब्दों का प्रयोग किया है। तुलसीदास वास्तव में ही उत्कृष्ट कोटि के भक्त कवि हैं।

दोहावली दोहों का सार

पाठ्यपुस्तक में तुलसीदास द्वारा रचित दस दोहे संकलित हैं, जिनमें कवि की भक्ति एवं नीति से संबंधित भावनाएँ व्यक्त हुई हैं। पहले दोहे में कवि अपने गुरु की वंदना कर अपने पवित्र मन से चारों फलों को देने वाला श्रीराम के पावन चरित्र के गुणगान करने की कामना करता है। दूसरे दोहे में श्रीराम रूपी मणियों के दीपक के प्रकाश से मन के अंधकार को दूर करने तथा तीसरे दोहे में संतों को नीर-क्षीर विवेकी हँसों के समान बताया गया है जो गुणों को अपना कर समस्त विकार त्याग देते हैं। चौथे दोहे में श्री राम की वानरों को सम्मान देने, पांचवें दोहे में श्रीराम के प्रति ममता तथा संसार के सभी लोगों से समता का व्यवहार रखने और छठे दोहे में संतों के समागम के लाभ का वर्णन किया गया है।

सातवें दोहे में दूसरों की संपत्ति को देखकर ईर्ष्या करने वालों की दुर्दशा का वर्णन है। आठवें दोहे में कवि ने राम भक्त हनुमान की प्रशंसा की है। नौवें दोहे में चापलूस सभासदों से राजा को सावधान रहने के लिए कहा गया है क्योंकि जी हजूरी करने वालों से धर्म, शरीर और राज्य का नाश हो जाता है। दसवें दोहे में कवि ने स्पष्ट किया है कि पूर्ण आस्था से भक्ति करने पर ही श्रीराम अपने भक्तों पर कृपा करते हैं तथा श्रीराम की कृपा के बिना स्वप्न में भी शांति नहीं मिलती है।

Punjab State Board PSEB 10th Class Science Important Questions Chapter 6 Life Processes Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 6 Life Processes

Long Answer Type Questions

Question 1.
What are the kinds of heterotrophic organisms on the basis of nutrition?
Answer:
Heterotrophic nutrition is a mode of nutrition in which organisms obtain readymade organic food from outside source. The organisms that depend upon outside sources for obtaining organic nutrients are called heterotrophs. It is a characteristic feature of all animals and non-green plants, that are unable to utilize carbon and synthesi s organic compounds necessary for life, but depends upon organic sources of carbon. They are thus dependent upon autotrophic organisms (Plants) and are called as heterotrophs.

It is of the following types :

• Saprophytic nutrition: In this type of nutrition, an organism lives upon dead organic sources such as dead plants and dead animals. These usually secrete dissolving and digesting enzymes and absorb the liquefied molecules so formed e.g. yeast, bread moulds and dung moulds etc.
• Parasitic nutrition: In this type of nutrition, an organism lives totally at the expense of others and derives its food material and shelter from the other .These organisms which derive food material are called parasites and the organism from which food is derived is called as host. This type of nutrition is termed as parasitic or holozoic nutrition: It is also known as parasite-host relationship e.g. Cuscuta, Ascaris etc.
• Holozoic nutrition. It is a mode of heterotrophic nutrition which involves intake of solid pieces of food. Since solid food is taken in, Holozoic nutrition is also called ingestive nutrition. Holozoic nutrition (GK. “Holo”-Whole; “Zoon”-Animal) is found in animals and protists. The food may consist of another animal, plant or its parts.

Depending upon the source of food, holozoic organisms are of three types :

1. Herbivores: These organisms obtain their food from plants e.g. cow, rat, deer and goat etc.
2. Carnivores: These organisms take the flesh of other organisms as their food e.g. tiger, cheetah, snake, eagle etc.
3. Omnivores: These can feed on plants and flesh of other organisms e.g. human, cockroach, crow etc.

Question 2.
What is photosynthesis? Describe the significance of photo-synthesis.
Answer:
Photosynthesis (Photos-Light, Synthesis-putting together) may be defined as an anabolic process in which green plants manufacture complex organic food substances (carbohydrate) from simple inorganic compounds like carbon dioxide and wrater in presence of sunlight with the aid of chlorophyll and evolve out oxygen as a byproduct of the process. Thus photosynthesis is a process in which radiant energy is converted into chemical energy

In other words photosynthesis is a series of oxidation- reduction reaction in which CO₂ is reduced and H₂O is oxidized to produce carbohydrates and oxygen.

• Chloroplasts are the actual sites for photosynthesis.
• All green parts of a plant are involved in photosynthesis.
• Leaves are the most important organs of photosynthesis.

Section of Leaf showing site of photosynthesis

Significance of photosynthesis:

• Photosynthesis is a source of all our food and fuel. It is the only biological process that acts as the driving vital force for the whole animal kingdom and for the non-photosynthetic organisms.
• It drives all other processes of biological and abio- logical world. It is responsible for the growth and sustenance of our biosphere.
• It provides organic substances, which are used in the production of fats, proteins, nucleoproteins, pigments, enzymes, vitamins, cellulose, organic acids, etc. Some of them become structural parts of the organisms.
• It makes use of simple raw materials such as CO₂, H₂O and inexhaustible light energy for the synthesis of energetic organic compounds.
• It is significant because it provides energy in terms of fossil fuels like coal and petrol obtained from plants, which lived millions and millions of years ago.
• Plants, from great trees to microscopic algae, are engaged in converting light energy into chemical energy, while man with all his knowledge in chemistry and physics cannot imitate them.

Question 3.
Which organelle is responsible for photosynthesis? Describe the role of chlorophyll.
Answer:
Chloroplast is the organelle responsible for photosynthesis. Chloroplasts contain green pigment called as chlorophyll. Photosynthetic pigments occur in the granum. They constitute the pigment system called photosystem. About 250 to 400 pigment molecules are present in a photosystem.

The primary function of photosystems is to trap light energy and converts it to chemical energy.

• Chloroplast was discovered by Schimper.
• Number of chloroplasts is variable in different species of plants.
• In lower plants like algae they are 1 or 2 number.
• In higher plants their number varies from 40 -100 per palisade cell or more.
• Chloroplasts also have variable shapes, for example cup-shaped, ribbon-shaped etc. in algae while it is discoidal in higher plants.

A typical structure of chloroplast is a double membranous structure having two parts.

• Grana: It is a lamellar system consisting of stacks of granum lamella each bounded by a membranous box called as thylakoid. They are 40 – 60 per cell. Number of thylakoids per grana is 50 or more. Chlorophyll molecules are found inside the thylakoid membrane where they trap solar energy in the form of small energy packets called ‘photon’ or ‘quanta’. Grana are interconnected to each other by a channel called as stroma lamellae or Fret’s channel.
• Stroma: It is a non-pigmented proteinaceous matrix in which grana remain embedded. It contains enzymes for dark reaction.
• Mechanism of Photosynthesis: Photosynthesis is formation of organic food from carbon dioxide and water with the help of sunlight inside chlorophyll containing cells. Oxygen is produced as by-products.

Oxygen comes from water. Hydrogen of water is used to reduce carbon dioxide to form carbohydrate.

Photosynthesis occurs in two main steps:

• The first step is dependent upon light and the second step is not dependent upon light. Hence, the former is called light reaction or photochemical phase while the latter, the dark reaction or biosynthetic phase of photosynthesis.
• Water is split up during photosynthesis by the process called photolysis. It provides reductant for carbon dioxide. Oxygen is liberated. All the liberated oxygen, therefore, comes from water.
• The photolysis of water in photosynthesis was discovered by Hill and hence it is also known as Hill reaction.
• The light reaction of photosynthesis is followed by the dark reaction. In this, CO₂ is first fixed by ribulose diphosphate and from this fixed CO₂ phosphoglyceric acid is formed. The phosphoglyceric acid thus formed ultimately forms carbohydrates.
• The basic organic compound formed in photosynthesis is often considered to be glucose. The storage product of plants is commonly starch.
• A chemical equation of photosynthesis is

In plants and most algae it occurs in the chloroplasts i.e., light reaction and dark reaction.

Question 4.
Discuss the steps of light reaction and dark reaction.
Answer:
Steps of light reaction.
Two main steps of light reaction are :
(a) Photolysis of water
(b) Conversion of fight energy into chemical energy.

• Light reaction takes places in the thylakoid membranes and the intergranal lamellae of the chloroplast in the presence of fight.
• Two photosystems (PSI and PSII) work in a coordinated manner.
• H₂O splits into H⁺ and OH^–.
• H+ is used to reduce NADP to NADPH₂ which is used in dark reaction.
• Photophosphorylation takes place in two ways—cyclic and non-cyclic.
• Light energy is converted into chemical energy.
• The end-products are ATP and NADPH₂.
• As a result of photolysis of water, oxygen is evolved as a by-product.
  4H₂O → 4 OH^– + 4 H⁺
  4 OH^– + 4e^– → 4 OH^–
  OH → 2H₂O + O₂

Summary of dark reaction :

• Dark reaction takes place in the stroma of the living chloroplast.
• Atmospheric CO₂ is absorbed.
• The end products of fight reaction (ATP and NADPH₂) are also used.
• All green plants operate C₃ photosynthetic pathway. Some monocot plants like maize, sugarcane operate both C₃ and C₄ photosynthetic pathways.
• First end product of photosynthesis is sugar.

Question 5.
Explain process of nutrition in Amoeba.
Answer:
Nutrition in Amoeba. Amoeba is omnivorous, i.e. it feeds on smaller animals, plants, micro-organisms and fragments of larger organisms. Nutrition is holozoic. Ingestion can occur at any place on the surface since a regular mouth is absent. Ingestion occurs through phagocytosis or engulfing the food particle in an invagination of the body. The engulfed food particle comes to fie inside a food vacuole. The latter is surrounded by a membrane.

Digestion of food within food vacuole

Digestion: The digestion is intracellular and the food vacuoles act as temporary stomach for digestion.
Absorption: It occurs by diffusion and distribution takes place by cyclosis.
Assimilation: Assimilation of digested material occurs in a single cell.
Egestion: The undigested food is eliminated through the surface of the cell, where the food vacuole containing the undigested food bursts and discharges its contents to the outside.

Question 6.
Difference between the followings :
(i) Autotrophic and Heterotrophic nutrition
(ii) Herbivore and Carnivore.
Answer:
(i) Autotrophic and Heterotrophic nutrition :

Autotrophic Nutrition	Heterotrophic Nutrition
1. Food is self-manufactured.	1. Food is obtained readymade from outside.
2. An external source of energy is required for synthesis of food.	2. An external source of energy is not required. The required energy is present in the food obtained from outside.
3. Inorganic substances constitute the raw materials for manufacturing food.	3. Inorganic substances are not much required.
4. Chlorophyll is present for trapping light energy.	4. Chlorophyll is absent
5. Digestion is absent.	5. An external or internal digestion is required for conversion of complex organic materials into simpler and soluble ones.
6. Organisms performing autotrophic nutrition function as producers. Examples: Green plants, some bacteria, some protists.	6. Organisms performing heterotrophic nutrition function as consumers. Animals, many protists and monerans.

(ii) Herbivore and Carnivore

Herbivore	Carnivore
Animals winch cat only plants. e.g. Cow, goat etc.	They feed on flesh of other animals, e.g. Lion, vulture etc.

Question 7.
Describe human alimentary canal. Draw a labelled diagram of human alimentary canal.
Or
Describe the human alimentary canal with the help of a suitable diagram.
Answer:

• Mammalian (human) alimentary canal comprises mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine (duodenum, jejunum and ileum), large intestine (caecum, colon and rectum) and anus.
• The mouth, bounded by two lips open into oral cavity.
• Buccal cavity contains teeth and tongue, and receives saliva from 3 pairs of salivary glands. Teeth are meant for cutting and mastication of food.
• Pharynx: It is a vertical tube. It is a cross passage for food and air. It has uvula and epiglottis which closes the internal nares and glottis respectively during swallowing of food to ensure the passage of food into oesophagus (food pipe).
• Oesophagus: It is a 25 cm long narrow muscular straight tube. It opens into stomach. Oesophagus propels the swallowed food into stomach.
• Stomach: It is a sac-like structure situated in the upper part of abdominal cavity below the diaphragm. Large part of this sac is situated left of the median line.
• Small Intestine: It is the longest part of alimentary canal. It is thin-walled and highly coiled tubular structure. It is about 3-3.5 metres long and occupies most part of abdominal cavity. It is coiled upon itself. Its inner lining is thrown into numerous villi.

Human digestive system.

Large intestine: The large intestine is about 1.5 metres long. It is divided into following parts, i.e. the vermiform appendix, the colon and the rectum. Caecum is a blind tube and represented by vermiform appendix (5-8 cm) and is present below the junction of small and large intestine. Rectum is the last part and opens to the outside by anus guarded by anal sphincter.

Question 8.
Describe the process of digestion of food in man.
Answer:
Digestion: The process of conversion of non-diffusible form of food into the simple and diffusible form by chemical and mechanical processes in the alimentary canal is called digestion.

• The process of digestion starts in the mouth cavity and is completed in the intestine.
• In the mouth, food gets mixed up with saliva secreted by salivary glands.
• Saliva contains an enzyme ptyalin (salivary amylase) which breaks polysaccharide starch into disaccharide maltose.

• The food from the mouth cavity called bolus passes into the stomach through the oesophagus.
• The gastric glands of the stomach secrete gastric juice which contains hydrochloric acid, protein digesting
• enzyme-pepsin Rennin, mucus and small amount of gastric lipase are also components of gastric juice.
• Pepsin breaks down proteins into peptones and proteoses in acidic medium of stomach.
• Rennin undies the milk.
• Muscles present on the wall of stomach churn and propel the food called chyme forward into duodenum.
• The digested food moves from stomach to duodenum of the small intestine.
• Duodenum receives bile from juices from liver and pancreatic juice from pancreas.
• The pancreatic juice contains trypsin, amylase and lipase.
• The proteins, fats and carbohydrates are further digested into diffusible form amino acids, glycerol and fatty acids, glucose and fructose.
• The intetinal juice consists of amylolytic, proteolytic and lipolytic enzymes.
• Finally, the digestion is completed in the ileum with the secretion of the intestinal juice by intestinal glands.
• Emulsion form of food called chyle is ready for absorption.

Question 9.
Name the constituents of blood and state the functions of each.
Answer:

Constituents	Functions
1. Plasma, (i) Serum	It contains proteins as well as organic and inorganic substances in solution.
(ii) Fibrinogen	It serves to carry the nutritive and waste materials, antibodies, enzymes and hormones.
2. Red blood corpuscles (R.B.Cs.)	Clotting of blood.
(Erythrocytes)	They help to transport oxygen.
3. White blood corpuscles (W.B.Cs)	They help to defend our body against bacteria, as well as the toxins which these organisms may produce. They also help to remove useless dead tissues from the blood.
4. Blood Platelets or Thrombocytes	They play a vey important role in bringing about the coagulation of blood.

Question 10.
State the functions of blood.
Answer:
Blood performs a number of functions in the body, the most important of which are as follows :

• Blood supplies nutrients and oxygen to various organs and cells of the body.
• It carries the waste matter formed in the cells to the excretory organs.
• It regulates the temperature of the body.
• It supplies hormones to different parts of the body.
• It prevents the body from various diseases by destroying the pathogenic germs.
• It prevents excessive loss of nutrients from cuts and wound by forming a clot.

Question 11.
Describe the structure of human heart.
Answer:
Heart.

• It is a highly efficient, pumping organ of body. Human heart consists of 4 chambers: upper smaller right and left atria (auricles) with thinner wall and lower larger right and left ventricles with thicker walls.
• Atria open into the respective ventricles by atrioventricular apertures guarded by atrioventricular valves.
• The two atria are separated from each other by interatrial septum, and the two ventricles are separated from each other by interventricular septum.
• The sinoatrial node (SAN) or the pacemaker is located in the upper wall of right atrium.

Valves of the heart.
Valves are muscular flaps which prevent the blood to flow back through it. Two types of heart valves are distinguished :

1. The Atrioventicular valves: These valves separate the atria from the ventricles. The right side of the heart possesses the tricuspid valve or right atrioventricular valve and the left side of the heart possesses the bicuspid or mitral valve.
2. Semilunar valves: These are located in the arteries leaving the heart. The pocket-shaped pulmonary semilunar valves lies in the opening where the pulmonary trunk leaves the right ventricle and aortic semilunar valve lies at the opening between the left ventricle and aorta.

Question 12.
Draw Human heart and label its parts.
Or
Draw a sectional view of the human heart and label on it, Aorta, Right Ventricle and Pulmonary veins.
Answer:
Human Heart

V.S. of Human heart.

Question 13.
Explain respiratory system of human.
Answer:

Human respiratory system

Question 14.
Describe the mechanism of breathing in human beings.
Answer:
Mechanism of breathing
Breathing. It is simply inhaling fresh air rich in oxygen and exhaling foul air rich in carbon dioxide. Respiratory system of man consists of :

1. Respiratory tract.
2. Respiratory organs (lungs).

Respiratory tract. It is the tract or the path through which fresh air enters the body reaches the lungs and foul air (rich in CO₂) leaves the lungs to come out. It consists of Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli (of Lungs).
Breathing is accomplished through changes in size and air pressure of chest cavity. It involves Inspiration and Expiration.

Inspiration:
Intake of fresh air is called inspiration. It occurs when the chest cavity is increased in size and therefore decrease in pressure.

Expiration:
The expulsion of foul air (rich in CO₂) from lungs is called expiration. It results when the chest cavity is reduced in size.

Question 15.
Draw a well labelled diagram of human excretory system.
Answer:
Human Excretory System.

Human excretory system.

Question 16.
Describe the structure of human urinary system.
Answer:
The urinary system consists of the following :

1. Kidneys
2. Ureters
3. Urinary bladder
4. Urethra.

1. Kidneys: The kidneys are a pair of bean-shaped delicate organs. They are situated one on each side of the mid-dorsal line of the abdominal cavity, just below the level of the stomach.

2. Ureters: They are two tubes about 30 cm long, emerging from each kidney with the pelvis of which they are continuous. The ureters run downwards and inwards and open into the urinary bladder.

3. Urinary bladder: It serves as a reservoir for the urine. It is a hollow muscular organ lined by stratified epithelium. Its average capacity for storage is about 500 mm. It is situated in the cavity of the pelvis just behind the pubic symphysis.

4. Urethra: The urethra in two sexes differ. The male urethra is about 20 cm in length. The female urethra is a short duct of about 4 cm long and it extends from the urinary bladder to the external urethra orifice which is in the vestibule just above and anterior to the vaginal orifice.

Short Answer Type Questions

Question 1.
What are life processes?
Answer:
Life processes: Every living organisms takes food, derives energy, removes wagte materials from their bodies and responds to changes in their environment. These activities are called life processes. In all living organisms there occur the basic life processes such as nutrition, respiration, transportation, excretion and reproduction, which are necessary for survival.

Question 2.
What is nutrition? Briefly explain the two major kinds of nutrition.
Or
Define autotrophic nutrition.
Answer:
Nutrition: All living organisms need matter to build up the body and energy to operate the metabolic reaction that sustains life. The materials which provide these two primary requirements of life are called nutrients or foods. The sum total of processes by which organisms obtain matter and energy is termed nutrition.

Modes of Nutrition:
1. Autotrophic or Holophytic nutrition: All green plants and certain protozoans (Euglena) have evolved a mechanism to directly use the energy7 of sunlight for preparing organic food in their own body from simple raw materials i.e. C02 and H20. These simple inorganic materials are transformed into glucose and oxygen is evolved.

2. Heterotrophic Nutrition: Animal, fungi, (Amoeba) and many bacteria cannot utilize solar energy. They use chemical bond-energy of organic molecules synthesized by other organisms in building their own organic molecules. Such a mode of feeding is termed as heterotrophic nutrition, and the organisms having it are called heterotrophs.

It is of three types :

1. Saprophytic
2. Parasitic
3. Holozoic.

Question 3.
Write a note on saprophytic nutrition.
Answer:
Saprophytic nutrition (Sapros = rotten; phyton = plant) It this organism releases some juices to soften or digest the food and then absorbs the nutrient. Thus they decompose the dead organic matter into simpler substance. Fungi (yeast, moulds, mushrooms) and many bacteria are saprophytic in nutrition.

The saprophytic mode of nutrition can best be exemplified by the common bread mould, Rhizopus. It converts the complex organic food materials of bread i.e. starch into soluble sugars with the help of starch digesting enzymes. These soluble sugars are then absorbed by the fungus.

Question 4.
Explain the two main steps of photosynthesis.
Answer:
Photosynthesis occurs in two main steps.

• The first step is dependent upon light and the second step is not dependent upon light. Hence, the former is called light reaction or photochemical phase while the latter, the dark reaction or biosynthetic phase of photosynthesis.
• Water is split up during photosynthesis by the process called photolysis. It provides reductant for carbon dioxide. Oxygen is liberated. All the liberated oxygen, therefore, comes from water.
• The photolysis of water in photosynthesis was discovered by Hill and hence it is also known as Hill reaction.
• The light reaction of photosynthesis is followed by the dark reaction. In this, CO₂ is first fixed by ribulose diphosphate and from this fixed CO₂ phosphoglyceric acid is formed. The phosphoglyceric acid thus formed ultimately forms carbohydrates.
• The basic organic compound formed in photosynthesis is often considered to be glucose. The storage product of plants is commonly starch.
• A chemical equation of photosynthesis is

In plants and most algae it occurs in the chloroplasts i.e., light reaction and dark reaction.

Question 5.
Give a brief account of factors affecting the process of photosynthesis.
Answer:
Factors affecting the process of photosynthesis.

• Temperature: The rate of photosynthesis increases with increase in temperature upto a maximum of 35°C. However, the rate starts decreasing if the temperature rises beyond 30°C.
• Water: The rate of photosynthesis is slow in water-deficient conditions.
• Carbon dioxide: The rate of photosynthesis increases with an increase in carbon dioxide concentration upto a certain level, beyond which there is no effect on the rate of photosynthesis.
• Anatomy of leaf
• Chlorophyll contents.

Question 6.
What are stomata? Explain role in respiration.
Or
How respiration takes place in roots and stems in plants?
Answer:
Respiration in plants. Plants, during the process of photosynthesis, give off oxygen which is utilized during respiration.

Plant respiration occurs at slower rate.

• In the leaves Stomata are the openings located on the surface of the leaves which are guarded by two kidney-shaped guard cells. Through stomatal opening, air can pass into or out of leaves.
• In woody stems. Lenticelo are the breathing pores located on the surface of the woody stems through which air can pass. Plants do not have any specialised ventilation mechanism.
• In roots. Roots take up oxygen present in between particles through root hairs by diffusion. Root hairs are simple extensions of epidermal cells of root in contact with soil.

In the older parts of roots: Older portions of root hairs lacks root hairs. They are covered with protective layer of dead cells having very small openings called lenticels through which gaseous exchange take place between soil and inner living cell.

Question 7.
Demonstrate with experiment that O₂ is evolved during photosynthesis.
Answer:
Take a beaker filled with water. Add a pinch of baking soda (NaHCO₃) to it and put a Hydrilla plant (Aquatic plant) in it. Cover the plant with a funnel. Invert a test tube containing water over the stem of the funnel. Keep this apparatus in the bright sunlight. After some time bubbles start emerging out from the plant, which gets collected in the upper part of the test tube. Remove the test tube and test the gas with a lighted splinter, it keeps on glowing showing that the gas is a supporter of combustion. Thus, the experiment clearly shows that O₂ is evolved during photosynthesis.

Question 8.
To demonstrate that photosynthesis take place in the presence of chlorophyll
Procedure :

• Take a potted plant with variegated leaves-for example, money plant or crotons.
• Keep the plant in a dark room for three days so that all the starch gets used up.
• Now keep the plant in the sunlight for about six hours.
• Pluck a leaf from the plant. Mark the green areas in it and trace them on a sheet of paper.
• Dip the leaf in boiling water for a few minutes.
• After this immerse it in a beaker containing alcohol.
• Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil.
• What happens to the colour of the leaf? What is the colour of the solution?
• Now dip the leaf in a dilute solution of iodine for a few minutes.
• Take out the leaf and rinse off the iodine solution.
• Observe the colour of the leaf and compare this with the tracing of the leaf done in the beginning (Fig.).

What can you conclude about the presence of starch in various areas of the leaf?

• Observation and Conclusion: Only green patches of variegated leaf take on blue colour. Other parts remain unchanged.
• Photosynthesis take place only in chlorophyll-containing patches of leaf.

Question 9.
To demonstrate that CO₂ necessary for photosynthesis.
Answer:
Procedure:

• Take two healthy potted plants which are nearly of the same size.
• Keep them in a dark room for three days.
• Now place each plant on separate glass plates. Place a watch-glass containing potassium hydroxide by the side of one of the plants.

The potassium hydroxide is used to absorb carbon dioxide.

Experimetal set-up (a) with potassium hydroxide (b) without potassium hydroxide

• Cover both the plants with separate bell-jars as shown in Figure.
• Use vaseline to seal the bottom of the jars to the glass plates so that the set-up is air-tight.
• Keep the plants in sunlight for about two hours.
• Pluck a leaf from each plant and check for the presence of starch as in the above activity.
• Do both the leaves show the presence of the same amount of starch?

What can you conclude from this activity?
Observation and Conclusion. The plant containing CO₂ in the surrounding carry out photosynthesis. Other plant does not. It proves that CO₂ is essential for photosynthesis.

Question 10.
Demonstrate with experiment that light is essential for photosynthesis.
Answer:
Take a de-starched potted plant, which has been kept in dark for 3 to 4 days. Cover one of its leaves completely with a carbon paper so that no light falls on it. Keep the plant in light for 4 to 6 hours. Test the covered leaf and uncovered leaf for starch with iodine test. The covered leaf will show negligible amount of starch, while the uncovered leaf will give positive test for starch. The process clearly shows that light is necessary for photosynthesis.

Question 11.
How is respiration different from breathing?
Answer:
Differences between Breathing and Respiration

Breathing	Respiration
1. It is ventilation or bringing in of oxygenated air and giving out deoxygenated air.	1. Respiration of animals includes breathing, gaseous exchange and catabolic breakdown of food.
2. It is a physical process.	2. Respiration is both a physical and physiological process.
3. Breathing does not liberate energy.	3. It liberates energy.
4. It is restricted to organs where gaseous exchange occurs between blood and atmospheric air.	4. Respiration involves every living ceil of the body.

Question 12.
List three differences between respiration in plants and respiration in animals.
Answer:
Differences in respiration in plants and animals

Respiration in plants	Respiration in animals
1. All the cells of plant parts (root, stem, leaves) perform the respiration individually.	1. It is performed by specific respiratory organs for all the cells of body.
2. There is little transport of gases from one part to the other.	2. Transport of gases is maximum.
3. Rate of respiration is low.	3. Rate of respiration is high.

Question 13.
What is the function of epiglottis?
Answer:
Epiglottis is a flap like structure present at the top of glottis. It closes glottis during swallowing of food thus checks the entry of food into respiratory passage.

Question 14.
Why is food necessary for living organisms?
Answer:
Food provide energy to raw materials for growth and maintenance.

Utility of components of food.

• Carbohydrates are mainly used for producing energy.
• Fats serve as stored concentrated fuel for energy production.
• Proteins are mainly used to build up tissues.
• Mineral salts and vitamins regulate metabolic processes and growth.
• Water is essential for all biological activities.

Question 15.
Explain the mechanism of breathing in human.
Answer:
Inhalation or Inspiration

• The entry of air from outside into alveoli of lungs through respiratory tract is called inhalation.
• The air enters when thoracic cavity expands due to contraction of intercostal muscles attached to ribs and peripheral muscles of the diaphragm.
• Thus the thorax moves upward, outward and forward.
• It increases the volume of thoracic cavity and the pressure decreases.
• Thus air from outside rushes into alveoli of lungs through nostrils, nasal chambers, trachea, bronchi and bronchioles.
• The alveolar sac gets filled with oxygen rich air.

Exhalation or Expiration is concerned with the expelling of carbon dioxide from lungs.

• It takes place when the volume of the thoracic cavity decreases and the pressure of the contained air in the thoracic cavity increases.
• Air passes out through the respiratory tract from the lungs.

Question 16.
What is the effect of sternuos exercise on rate of breathing and why?
Answer:
Normally man breathes about 15-18 times per minute but during hard exercise the breathing rate increases to 20 to 25 times per minute. It is due to the fact that body needs more of energy thus requires more of oxygen.

Question 17.
Give an outline of Calvin-Benson Cycle.
Answer:
Melvin Calvin and Andy Benson discovered this cycle, hence it is called Calvin cycle.

Calvin-Benson Cycle

Question 18.
Label the parts in the figure.
Answer:

Answer:

1. Pseudopodium
2. Food particle
3. Ingestion
4. Food Vacuole
5. Waste
6. Digestion of food.

Question 19.
Describe the role of intestinal juice.
Answer:
Intestinal juice too is alkaline (pH 8.3).

It has many enzymes :

• Intestinal amylase hydrolyses the remaining starch and glycogen to maltose.
• Maltase changes maltose to glucose.
• Sucrase converts sucrose into glucose and fructose.
• Lactase hydrolyses lactose to glucose and fructose.
• Dipeptidases hydrolyse dipeptides to amino acids.
• Intestinal lipase splits emulsified fats into fatty acids and glycerol.
• Alkaline emulsion of digestion products formed in the small intestine is called chyle.

Question 20.
Explain absorption of food in the small intestine.
Answer:
Absorption. The process of diffusion of digested food into blood present in the blood capillaries of smail intestine is called absorption. Inner lining is thrown in fold called villi. They increase surface area for absorption of food.
Glucose, amino acid, vitamins, mineral salts and water diffuses into blood present in blood capillaries of numerous villi of the small intestine. The fatty acids and glycerol diffuses into lymph present in lymph vessels called lacteals. The digested food is carried to the liver by the hepatic portal vein. The fatty acid and glycerol unite in lymph to form fat. Most of the fat passes as a milky emulsion. After absorption, the undigested- food passes into large intestine.

Question 21.
State the functions of stomach and large intestine.
Functions of Stomach
Answer:

• Storage of food.
• Mechanical breakdown of food.
• Partial digestion of food.

Functions of large intestine
Colon:

• Its wall absorbs the water from undigested food.
• Absorption of digested food also takes place in this region which has not been absorbed by ileum.

Question 22.
Differentiate the following :
Respiration and Photosynthesis
Answer:
Differences between Respiration and Photosynthesis

Respiration	Photosynthesis
1. It is a catabolic process in which food substrates are broken down.	1. It is an anabolic process in which food substrates are synthesized.
2. It takes place in all living cells.	2. It is carried out only by the chlorophyll containing cells of plants.
3. CO2 and H2O are produced.	3. CO2 and H2O are used.
4. CO2 is given out.	4. O2 is released as a byproduct.
5. Chemical energy is converted into ATP and some energy is lost as heat.	5. Radiant energy’of light is converted into 1 chemical energy.

Question 23.
What is fermentation? How is it important?
Answer:
The slow decomposition of organic matter into simpler substances in the presence of enzymes is known as fermentation. It is a type of anaerobic respiration. Fermentation literally means a chemical change accompanied by effervescence. The anaerobic breakdown of glucose to carbon dioxide and ethanol is a form of respiration referred to fermentation. It is normally carried by yeast cells and accounts for the production of alcohol in alcoholic bevefages. In fermentation process, if glucose is converted into ethanol then it is called ethanolic fermentation. When glucose is converted into organic acids such as lactic acid, then this type of fermentation is known as lactic acid fermentation. It is carried out by the bacterium Bacillus acidilacti.

Question 24.
Briefly explain the human respiratory system and also label the parts 1, 2, 3, 4, 3 and 6.

Answer:
Human Respiratory System. Respiratory system of human beings and other mammals consists of air passage or respiratory tract, a pair of lungs.

Respiratory tract is made up of nostrils nasal cavity, pharynx, larynx, trachea and bronchi.

1. Left Lung
2. Heart
3. Diaphragm
4. Trachea
5. Larynx
6. Nasal Cavity

The lungs are a pair of brownish grey coloured spongy structures situated in the thoracic cavity. The left lung consists of two lobes while the right lung consists of three lobes.

Each lobule of a lung consists of bronchioles which terminate into a bunch of spherical thin walled air sacs, called alveoli.

Each alveolus or air sac has a diameter of 75 to 300 microns and has a very thin wall. The walls of the alveoli are elastic and are supplied with capillaries. Gases are exchanged between the capillaries and the air sacs through these thin walls.

Question 25.
What are the different modes of respiration in animals?
Answer:
In animals such as earthworm, respiration is by skin.

• The insects have an elaborate tracheal system of respiration.
• Fishes respire through gills.
• Respiratory system of human beings and other mammals consists of air passage or Respiratory tract, and a pair of lungs.
• Respiratory tract is made up of nasal cavity, pharynx, larynx, trachea and bronchi. The lungs are a pair of brownish grey coloured spongy structures situated in the thoracic cavity.
• The left lung consists of two lobes while the right lung consists of three lobes.
• Each lobule of a lung consists of bronchioles which terminate into a bunch of spherical thin-walled air sacs, called alveoli.

Question 26.
Differentiate between respiration and combustion.
Answer:
Difference between respiration and combustion.

Respiration	Combustion
1. It occurs in living cells.	1. It occurs in non living and dead cells.
2. It is a complex biochemical process controlled by several enzymes.	2. It is a chemical process.
3. Heat produced is much less.	3. A large amount of heat is produced.
4. There is no flame or light produced.	4. This process is usually accompanied with flame and light.

Question 27.
What are parasitic nutrition?
Answer:
Parasitic nutrition (Para = besides ; sitos = food). In this an organism (parasite) depends upon the organism (host) for its nutritional requirements. Many bacteria, viruses, fungi, some non-green plants and many animals have this mode of nutrition.

For example, a fungus Puccinia is a parasite on wheat and barberry plants; Cuscuta or dodder plant grows as a parasite on many plants; tapeworms and round worms are parasites in the body of man etc.

Parasites are of two kinds :

1. Ectoparasites and
2. Endoparasites

Question 28.
Differentiate between Light reaction and Dark reaction in photosynthesis.
Answer:
Difference between light reaction and Dark reaction

Light reaction	Dark reaction
1. Light reaction is light induced chemical reaction.	1. Dark reaction requires no light and is purely enzyme controlled reaction.
2. Energy rich compounds like ATP and NADPH2 are synthesized.	2. The energy rich compounds are used to produce the organic compounds.
3. Oxygen is liberated.	3. No liberation of oxygen.
4. It takes place in the grana of the chloroplasts.	4. It takes place in the stroma of chloroplasts.

Question 29.
What are the functions of liver?
Answer:
Functions of liver

1. Role in digestion. Bile produced by liver helps in the digestion of food as follows.
   • It emulsifies the fats with its salts.
   • It prevents decomposition of food by checking the growth of bacteria.
   • It neutralizes the acid coming from the stomach along with food and provide alkaline medium in the intestine required for action of enzymes of pancreas and intestinal glands.
2. Regulation of Blood Sugar: The liver separates the excess of sugar from the blood and stores it in its cells as glycogen (animals starch).
3. Formation of Glycogen from non-carbohydrates Sources.
4. Deamination: In the liver, the amino acids coming from the alimentary canal are sorted out, ammonia is formed. Ammonia is converted to less toxic urea.
5. Excretion: Liver collects haemoglobin of the worn-out red blood corpuscles and changes it into bile pigments.

Question 30.
Differentiate between Saprophytic and Parasitic nutrition.
Answer:

Saprotrophic Nutrition

Parasitic nutrition

Many organisms absorb fluid food through the body surface. This is called saprotrophic nutrition. Bacteria and fungi flourish on dead, decaying organic matter of both plant and animal origin. They secrete digestive enzymes onto this matter. The enzymes hydrolyze the organic matter into simple soluble products that are then absorbed. This method of taking up organic food is known as saprophytic nutrition.

The organisms obtain nutrients from a living host without helping it any way. Examples. Liver fluke lives in the bile duct of sheep and absorbs nutrient. Other examples include several fungi, bacteria and a few higher non-green plants such a cuscuta.

Question 31.
Discuss the fate of food in the oral cavity of man.
Answer:
Fate of food in mouth cavity. The partial digestion of food occurs due to the action of Ptyalin enzyme. It acts on starches and forms maltose.
The sufficiently masticated, partially digested food forms bolus. It is swallowed into oesophagus through gullet by raising the throat aided by the muscles of pharynx.

Question 32.
What is a digestive gland? Name the various digestive glands of man and their secretions.
Answer:
Digestive gland. A gland that secretes digestive juice which is helpful in the digestion of food is called a digestive gland.

Digestive glands of Man

Name of digestive gland	Name of digestive juice/Secretion
1. Salivary gland	Saliva
2. Gastric glands	Gastric juice
3. Pancreas	Pancreatic juice
4. Liver	Bile
5. Intestinal glands	Intestinal juice

Question 33.
Write the enzymes of the pancreatic juice, the substrates they digest and the products of their digestive action.
Answer:
Enzymes of the pancreatic juice

Name of Enzyme	Substrate	Name of end products
1. Amylase	Starch, glycogen	Maltose and Isomaltose
2. Trypsin	Proteoses, Peptones and Proteins	Peptides and amino acid
3. Lipase	Emulsified lipids	Glycerol and fatty acids

Question 34.
What is meant by photosynthesis? What are the basic requirements for the process of photosynthesis?
Answer:
The manufacture of organic compounds from carbon dioxide and water in the presence of sunlight inside the chlorophyll containing cells of the plant is called photosynthesis. The overall reaction of photosynthesis is

Basic requirements for photosynthesis. CO2, water, chlorophyll and solar energy. Photosynthesis is a photo-biochemical process in which energy rich compounds such as carbohydrates (glucose) are synthesized from simple inorganic compounds like CO2 and water in the presence of sunlight and chlorophyll. Oxygen is a by-product.

Question 35.
What are the different ways in which glucose is oxidized to provide energy in various organisms?
Answer:
Breaking down of glucose involves two step process. In the first step, it is broken into three carbon molecule called pyruvate. The pyruvate is further broken down into energy in following different ways in various organisms :

• Aerobic Respiration: In this case, pyruvate is broken down into water and carbon dioxide along with release of energy. It commonly occurs in mitochondria of cells.
• Anaerobic Respiration in Yeast: In yeast cells during fermentation pyruvate is converted into ethanol and carbon dioxide in the absence of oxygen.
• Anaerobic Respiration in Muscles: Due to lack of oxygen, e.g. during vigorous running or exercise, in human muscles, pyruvate is converted into lactic acid.

Question 36.
Explain how exchange of materials takes place between Blood and Tissues.
Answer:
Arteries supply fresh blood with 02 and food materials to different body organs. Inside the body organ the artery divides into smaller branches called arterioles. The arterioles further divide into extremely thin walled blood capillaries. The blood capillaries form an extensive network inside the body organ. They make their way through the tissue cells. Blood plasma along with the dissolved materials comes out of the thin walls of the blood capillaries and collects into the tissue. It is then called tissue fluid, which acts as an intermediate medium between blood and tissue cells.

The tissue fluid contains different materials such as oxygen, amino acids, glucose, mineral ions and proteins etc. which are needed by the body cells. The body cells take up the required materials from the tissue fluid and release their wastes such as C02 and nitrogenous wastes. These enter through the blood capillary wall and dissolve into the blood plasma or enter into the red blood cells and are carried away.

Question 37.
Outline inhalation-exhalation cycle.
Answer:

• Inhalation: Lowering of diaphragm → Rising of rib cage → Gas (O₂) passes to Alveoli
• Exhalation: Air is forced out → Rising of diaphragm → Lowering of ribcage

Question 38.
Leaves of a healthy potted plant are coated with vaseline to block the stomata. Will this plant remain healthy for long? State three reasons to support your answer.
Answer:
No, the plant will not remain healthy because no exchange of gases will take place. It will lead to :

• low respiration
• no photosynthesis occurs
• no transpiration.

Hence plant will not remain healthy and may die eventually.

Question 39.
What are
(i) stomata and
Answer:
Stomata are tiny apertures found on the surface of the leaf, which regulate the exchange of respiratory gases and transpiration.

(ii) lenticels?
Answer:
Lenticels are the raised pores in the woody plants that allow the exchange of gases between the atmosphere and the internal tissues.

Question 40.
Briefly explain breathing, external resperation exchange of gases and tissue resperation.
Answer:

• Breathing involves inhaling of oxygen rich fresh air and exhaling of carbon dioxide rich foul air. The respiratory surface is richly supplied with blood for this purpose. Oxygen of the inhaled air is taken up by blood while carbon dioxide of the blood passes into the air for exhalation.
• The exchange of gases between the blood and the air at the respiratory surface is. known as external respiration.
• Oxygen absorbed by the blood at the respiratory surface is taken to various parts of the body through arteries. Blood loses the oxygen contained in it to tissue fluid, from where it picks up carbon dioxide. The latter is brought to the respiratory surface by blood.
• Tissue respiration, also called internal respiration, is the exchange of gases between the tissue cells and the blood involving uptake of oxygen by tissue cells, oxidation of respiratory substrate and elimination of carbon dioxide by the cells.

Question 41.
Why is mitochondria termed ‘power house’ of the cell?
Answer:

• Most of the aerobic respiration occurs inside the mitochondria and therefore, the latter are also called power houses of the cells.
• Mitochondria are site of synthesis, storage and transport of ATP.
• ATP (Adenosine triphosphate) is the energy currency of the living organisms.
• Adenosine triphosphate. The energy released during cellular respiration is immediately used to synthesise a molecule called ATP from ADP and inorganic phosphate

ATP is used to fuel all other activities in the cell. Therefore, it is said to be the energy currency for . most cellular processes.

Question 42.
The figure shows different ways in which glucose is oxidised to provide energy in various organisms?
Fill up the blanks : A _________ B _________ C _________, D. _________ E _________ F _________

Answer:
Different pathways to provide energy from glucose
A. glucose
B. Pyruvate
C. Absence of Oxygen
D. Presence of oxygen
E. Lactic Acid F. Carbondioxide

Question 43.
Fill in the blanks 1, 2, 3, 4, 5, 6 in the figure.

Double circulation of blood in birds and mammals.
Answer:

1. Right vetricle
2. Lungs
3. Left Auricle
4. Left Ventricle
5. Body parts (except Lungs)
6. Right Auricle

Question 44.
State differences between artery and vein.
Answer:
Differences between Artery and Vein

Artery	Vein
1. An artery carries blood from the heart to different organs of the body.	1. A vein collects blood from different organs of the body and brings it back to the heart.
2. Blood flows under great pressure.	2. Blood flows under less pressure.
3. It has a thick muscular wall.	3. Wall is thin
4. It is non collapsible.	4. It is collapsible.
5. It contains oxygenated blood (Exception pulmonary artery).	5. It contains deoxygenated blood (Exception pulmonary vein)
6. Valves are absent.	6. Valves are present.
7. Mostly deep seated.	7. Mostly superficial.

Question 45.
Why are WBCs called ‘soldiers of the body’?
Answer:
WBC (White Blood Corpuscles) or leucocytes engulf and destroy the foreign particles in the body. Hence they are called ‘soldiers of the body.’

Question 46.
What are hypertension and hypotension?
Answer:
Hypertension. It is the high blood pressure which is caused due to emotions such as worry, excitement, fear etc.
Hypotension. It is the low blood pressure when it falls below the normal level.

Question 47.
Name the three major types of blood vessels. Explain briefly.
Answer:
The three main types of blood vessels are :

• Arteries have thick elastic walls and their diameter may be even 1 cm. These blood vessels carry the blood from the heart to the various parts of the body.
• Capillaries. Arteries divide into thin arterioles and arterioles further ramify into capillaries (1 micron diameter). The wall of a capillary is made up of a single layer of cells. The muscles and elastic fibres are absent in the capillaries. The walls of these capillaries are so thin that the exchange of food materials, waste materials and gases takes place between the blood and protoplasm of cells (liver, lung etc.) through them.
• Veins. The capillaries again reunite to form venules and venules unite to form veins. These venules and veins return the blood to the heart.

Diagram showing the relationship among blood vessels

Question 48.
Write a note on lymphatic system in human beings.
Answer:
Lymphatic system: The lymphatic system comprises colourless fluid, the lymph; a network of fine channels, the lymphatic capillaries; tubes of varied sizes, the lymphatic vessels; and the lymph nodes. Tissue or interstitial fluid present in the spaces between tissue cells is formed by filtration of protein-free fluid from the blood. Tissue fluid passes into lymphatic capillaries to form lymph. The latter is carried by lymphatic vessels to the veins. Lymphatic vessels have lymph nodes which filter lymph, removing microorganisms and cellular debris and adding lymphocytes.

Question 49.
Write functions of lymph.
Answer:
Functions of lymph

• It drains excess tissue fluid from the extracellular spaces back into the blood.
• Some of the fluid from the digestive tract is absorbed in the lymph. The lymphatic vessels store this fluid temporarily, and release it gradually so that the kidneys do not face a sudden pressure of urine excretion.
• It carries carbon dioxide and nitrogenous waste materials that diffuse into the tissue fluid to the blood.
• It takes lymphocytes and antibodies from the lymph nodes to the blood.

Question 50.
Give differences between blood and lymph.
Answer:
Differences between Blood and Lymph

Blood	Lymph
1. It consists of plasma, erythrocytes, leucocytes and platelets.	1. It consists of plasma and leucocytes (lymphocytes most abundant).
2. It is red in colour due to the presence of haemoglobin in erythrocytes.	2. It is colourless as haemoglobin is absent,
3. Its plasma has more proteins, calcium and phosphorus.	3. Its plasma has fewer proteins and less calcium and phosphorus.
4. It transports materials in the body.	4. It acts as middle man between blood and body tissue.

Question 51.
How are xylem and phloem well suited for transport of materials in plants? Explain.
Or
How are water and mineral transported in plants?
Answer:
Xylem and phloem are well suited to carry water, minerals and food in plants. Vessels in the xylem are cylindrical in shape with their ends open and are placed one above the other so as to form a continuous column stretching from roots to leaves. So, the water and minerals absorbed by the roots are carried upwards to the leaves. This is known as transportation.

Similarly, phloem has sieve tubes that are also cylindrical but the ends are not open instead covered with sieve (perforated) plate. These tubes are also placed one above the other, forming a continuous column from leaves to other parts of the plant body. The food synthesized in the leaves is carried to other paxts of the plant body through phloem. Sucrose is the main form in which carbohydrates are translocated in plants.

Xylem vessels that transport water and mineral sahs

Phioem tubes that conduct prepared food.

Question 52.
Mention any three methods adopted by plants to minimise the transpiration rate.
Answer:
Three methods adopted by plants to minimise the rate of transpiration are :

1. In some cases leaves are rolled to cover stomata (e.g. some grasses)
2. The stomata may be sunken (e.g. Nerium)
3. In some cases, leaves may be dropped or absent as in most cacti.

Question 53.
Write a short note on root pressure.
Answer:
Root pressure: During absorption, water is forced into the xylem vessels by the surrounding cortical cells with a certain force. This induces a pressure which is responsible for ascent of sap to many feet in xylem. This pressure which is developed due to the activity of root is called as root pressure.
Root pressure is a vital phenomenon and depends upon the activity of living root cells. The magnitude of root pressure varies from 2-8 atm.

Question 54.
How is transpiration useful to plants?
Answer:
Advantages of transpiration

• It has cooling effect on the plants as excess of sun’s energy is dissipated.
• It helps in the removal of excess of water from the plant.
• It causes ascent of sap.
• It helps to maintain water cycle.
• It increases the amount of sugar and mineral content in the fruit.
• It is needed to permit photosynthesis to take place.

Question 55.
What are the disadvantages of transpiration?
Answer:

• More plants die from excessive water loss by transpiration.
• Due to high rate of transpiration plants suffer from loss of turgidity.

Question 56.
What is translocation?
Answer:
Translocation: The long distance transport of the organic food from a source to a sink is known as translocation.

Question 57.
(a) What is blood pressure?
Answer:
Blood pressure is the force that blood exerts against the wall of a vessel. This pressure is much greater in arteries than in veins. The pressure of blood inside the artery during ventricular systole is called systolic pressure and pressure in artery during ventricular diastole is called diastolic pressure.

(b) What are normal value of systolic and diastolic blood pressure
Answer:
The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.

(c) How is it measured?
Answer:

Measurement of blood pressure

(d) Name the instrument used to measure blood pressure.
Answer:
Blood pressure is measured with an instrument called sphygmomanometer.
High blood pressure is also called hypertension and is caused by the constriction of arterioles, which results in increased resistance to blood flow. It can lead to the rupture of an artery and internal bleeding.

Question 58.
Write a note on mechanism of blood clotting.
Answer:
Blood Clotting: At the site of injury, blood platelets disintegrate and release enzyme thromboplastin. Thromboplastin in the presence of calcium ions, transforms the inactive prothrombin into active thrombin. Thrombin converts soluble fibrinogen into insoluble fibrin. This forms a meshwork of fibrils which entangle blood corpuscle and transforms the liquid blood into a gel or clot.

Mechanism of Blood Clotting
Unless the blood clots at the site of the injury, there will be loss of blood (blood haemorrhage).
Such a loss of blood will lead to death of the person.

Question 59.
Briefly describe excretory system.
Answer:

• Kidneys are a pair of bean-shaped reddish brown organs which lie in the lumbar part of abdomen along the dorsal wall, one on either side of the vertebral column.
• Each kidney receives a renal artery from dorsal aorta and sends a renal vein to inferior vena cava.
• The excretory waste products ,are filtered out in the kidney.
• Each kidney contains about 1.2 million excretory units called uriniferous tubules or nephrons.
• Uriniferous tubule is a long, twisted, narrow, tubular structure which consists of ‘ Bowman’s capsule, neck, proximal convoluted tubule, loop of Henle and distal convoluted tubule.
• Bowman’s capsule is a blind cup-shaped end of uriniferous tubule with a tuft of blood capillaries called glomerulus.
• Ureters are two distensible tubes which connect the kidneys with the urinary bladder.
• Urinary bladder is a median pear-shaped bag-like structure that occurs in she pelvic region of abdominal cavity.
• Urinary bladder can hold 300-800 ml of urine.
• Urethra is a tubular connection between the urinary bladder and the external Opening of urinary tract.

Question 60.
Label the parts of human excretory system.
Answer:

1. Kidney
2. Ureter
3. Urinary Bladder.

Question 61.
How does the excretion take place in Amoeba?
Answer:
The excretory product of Amoeba is ammonia. Special excretory organelle is lacking in Amoeba. C02 and ammonia are excreted by diffusing in solution through plasma membrane. The concentration of ammonia is always higher in Amoeba than in the surrounding water. The water enters through plasma membrane by “endosmosis”. Ammonia is formed in cytoplasm by metabolism.

Surplus water enters contractile vacuole. This surplus water can rupture the animal’s body. Thus size of contractile vacuole increases, when the contractile vacuole is fully expanded with water, it moves towards the periphery. As the contractile vacuole comes in close contact with the plasma membrane, it bursts. Thus excess of water (surplus water) is discharged in the surrounding water. This phenomenon of controlling the amount of water in the body is called as “osmoregulation”.

Excretion in Amoeba

Question 62.
State one main function of the following :
(i) Glomerulus
Answer:
The filtration of blood in the nephron takes place in the glomerulus.

(ii) Malpighian capsule
Answer:
Malpighian capsule is concerned with ultrafiltration.

(iii) Sweat gland
Answer:
Sweat glands produce sweat containing urea, uric acid and salts. Sweat evaporates to bring down the body temperature to normal.

(iv) Nephron of kidney tubule
Answer:
Through the kidney tubule or nephrons, filtration of urea, uric acid, water and some salts occur from the blood.

(v) Loop of Henle.
Answer:
Loop of Henle is useful in the absorption of water and secretion of urea.

Question 63.
Name the chief organs of excretion in man. Mention the waste products that they excrete.
Answer:
The chief excretory organs and the waste products removed by them are :

1. Kidneys – Urea in the form of urine.
2. Lungs – Carbon dioxide.
3. Skin – Water and salts as sweat.

Question 64.
Name the following :
(i) A process by which the unwanted nitrogenous wastes are eliminated from the body.
Answer:
Excretion

(ii) Major excretory organs of man.
Answer:
Kidneys

(iii) The structural and functional units of kidney.
Answer:
Nephrons

(iv) A tuft of blood capillaries found in the Bowman’s capsule of nephron.
Answer:
Glomerulus

Question 65.
Name the following :
(i) The structure that brings urine from the kidney to the urinary bladder.
Answer:
Ureter

(ii) Thin membranous sac serving as the reservoir of urine.
Answer:
Urinary bladder

(iii) Any two organic constituents of normal human urine.
Answer:
Urea, creatinine

(iv) The chief nitrogenous waste product in the human urine and the organ which produces it.
Answer:
Urea, liver

(v) Name two excretory products formed by the liver.
Answer:
Bile pigments (Bilirubin, Biliverdin), urea.

Question 66.
What do you understand by artificial kidney? Name the principle on which it works.
Or
Write a note on haemodialysis.
Answer:
Artificial Kidney or Haemodialysis. In case of acute kidney failure, the poisonous materials may accumulate in the body fluids which will cause oedema and finally lead to death of the patient. In such cases, artificial kidney is used. It works on the principle of dialysis and separates wastes from the blood. The process is called haemodialysis.

Artificial kidney contains a number of tubes with a semipermeable lining.
Its functioning is similar to kidney, but it is different since there is no reabsorption involved.

In this, blood from an artery is diverted through a cellophane tube, having pores equal to those of glomerular capillaries, placed in a circulating bath. Concentration of bath-fluid is kept equal to that of normal plasma. The pores in the cellophane tube allow small sized wastes like urea, ammonium salts etc. to pass through but do not allow the passage of blood cells, proteins, fats etc. Diffusion of small and useful substances like glucose, amino acids etc is prevented by keeping their concentration in the dialysis fluid equal to the normal plasma. Blood from dialyser is returned to the body through a vein.

Flow of blood through an artificial kidney for haemodialysis.

Question 67.
What are the functions of tongue?
Answer:
Functions of tongue.

• It helps in mastication of food.
• It bears taste buds and helps in the sensation of taste of food.
• It takes part in the modification of sound production.
• It acts as a brush and cleans the teeth.
• It aids in deglutition of food.

Question 68.
(i) Label the part A-E
Answer:

A. Interventricular System B. Right Ventricle C. Right Atrium D. Left Ventricle E. Aorta

(ii) Write Function of E.
Answer:
Function of E-Aorta carries blood to all parts of body.

Very Short Answer Type Questions

Question 1.
Why are maintenance processes required?
Answer:
They are required to prevent breakdown.

Question 2.
List three characteristics of living organisms.
Answer:

1. Growth
2. Movements
3. Repair and maintenance of their structures.

Question 3.
What are life processes?
Answer:
The processes which together perform the maintenance jobs are collectively termed as life processes.

Question 4.
What is the basic requirement of maintenance?
Answer:
Energy is needed by living organisms for maintenance.

Question 5.
What are sources of energy for living organisms?
Answer:
Carbon based molecules i.e. food obtained from environment.

Question 6.
List the common reactions required to obtain energy from carbon based molecules.
Answer:
Oxidising-reducing reactions.

Question 7.
Name any four life processes required for maintenance.
Answer:

1. Nutrition
2. Respiration
3. Transportation
4. Excretion.

Question 8.
What are nutrients?
Answer:
The substances which provide materials for growth, energy and maintenance are called nutrients.

Question 9.
What is nutrition? Why is it necessary?
Answer:
Nutrition. The sum total of processes by which living organisms obtain food materials and prepare them for use in the growth, repair and providing energy is termed nutrition.

Question 10.
What is food?
Answer:
Food provides energy. It Provides raw materials for growth and maintenance.

Question 11.
What is holozoic nutrition?
Answer:
Holozoic nutrition. When the nutrients are ingested as solid organic food matter, it is called holozoic nutrition.

Question 12.
What is the source of food for heterotrophs?
Answer:
All heterotrophs obtain food from autotrophs.

Question 13.
Name the process which prepares food is autotrophs.
Answer:
Photosynthesis.

Question 14.
Why are green plants called producers?
Answer:
Green plants prepare their food from CO₂ and H₂O in the presence of sunlight and chlorophyll. All other organisms obtain food from green plants, thus called as producers.

Question 16.
In which spectrum of light maximum photosynthesis occurs?
Answer:
Red light.

Question 17.
Where is chlorophyll present in cells of leaves?
Answer:
Chloroplast.

Question 18.
How does oxygen produced during photosynthesis enter the atmosphere?
Answer:
Oxygen passes out of green leaves through stomata and diffuses into the atmosphere.

Question 19.
Where does photolysis occur in plant?
Answer:
Photolysis occurs in chloroplasts present in the cell.

Question 20.
Write chemical reaction of photosynthesis.
Answer:

Question 21.
What are the advantages of cooked food?
Answer:
Human beings consume cooked food. Cooking makes it soft, palatable, tasty and easier to digest.

Question 22.
What is the role of CO₂ during photosynthesis?
Answer:
CO₂ provides carbon for synthesis of glucose (C₆H₁₂O₈) during photosynthesis.

Question 23.
What is the role of stomata in green leaves?
Answer:
Stomata are minute pores through which exchange of gas occurs.

Question 24.
Name the minerals obtained from soil by plants.
Answer:
Nitrogen, phosphorus, potassium, iron, magnesium and other minerals.

Question 25.
What is the role of nitrogen plants?
Answer:
Nitrogen is constituent of proteins and nitrogen bases of nucleic acids.

Question 26.
What is the food of Amoeba?
Answer:
Food of Amoeba consists of small protozoans, algae, rotifers, bacteria, and diatoms. It also feeds upon bits of organic matter.

Question 27.
Is food vacuole of Amoeba, temporary structure or a permanent one?
Answer:
Food vacuole is a temporary structure.

Question 28.
What is saliva?
Answer:
Saliva is a digestive juice secreted by salivary glands present in oral cavity.

Question 29.
Name the enzyme present in saliva.
Answer:
Salivary amylase.

Question 30.
Name the organ through which blood passes into stomach from oral cavity.
Answer:
Pharynx and oesophagus.

Question 31.
Name the largest part of alimentary canal.
Answer:
Small intestine.

Question 32.
Which of the animals need long large intestine?
Answer:
Animals eating grasses need large intestine for digestion of cellulose.

Question 33.
What is the nature of food entering small intestine from stomach?
Answer:
Acidic in nature.

Question 34.
Name the juices which convert acidic food into alkaline in small intestine.
Answer:
Bile and pancreatic juice.

Question 35.
Name the digestive juice secreted by liver.
Answer:
Bile juice.

Question 36.
Name the digestive juice secreted by pancreas.
Answer:
Pancreatic juice.

Question 37.
List the enzymes which help in the digestion of proteins.
Answer:

• Pepsin
• Trypsin
• Chymotryposin
• Peptidases.

Question 38.
What is approximate length of human alimentary canal?
Answer:
9 to 10 metres.

Question 39.
Name the largest gland present in human body.
Answer:
Liver.

Question 40.
Name the gland which is exocrine as well as endocrine in nature.
Answer:
Pancreas.

Question 41.
What are three parts of small intestine?
Answer:

1. Duodenum
2. Jejunum
3. Ileum.

Question 42.
Differentiate between chyme and chyle.
Answer:

• Chyme is a semisolid, semidigested acidic food which passes from stomach into duodenum.
• Chyle is emulsion form, completely digested, alkaline food present is small intestine ready for absorption.

Question 43.
Name the four enzymes present in pancreatic juice.
Answer:

1. Pancreatic amylase
2. Pancreatic lipase
3. Trypsin
4. Chymotrypsin.

Question 44.
Maximum water is absorbed in which part of alimentary canal.
Answer:
Large intestine.

Question 45.
What is digestion?
Answer:
Digestion. Chemical and mechanical break down of complex, non-diffusible form of food into simple diffusible form of food by action of enzyme.

Question 46.
What is assimilation?
Answer:
The absorption and digestion of food or nutrients by the body or any biological system.

Question 47.
What is egestion?
Answer:
The act or process of discharging undigested food as faeces from a cell in case of unicellular organisms.

Question 48.
What are villi present is small intestine and not in stomach?
Answer:
Small intestine is site of absorption of digested food, villi increase the surface area for absorption of food. No absorption of food occurs in stomach thus villi are absent.

Question 49.
What happens to pyrnvate produced during anaerobic respiration?
Answer:
Pyruvate produced at the end of glycolysis is converted to C02 and ethanol.

Question 50.
What is aerobic respiration?
Answer:
Aerobic respiration is the process of producing cellular energy involving oxygen cells break down food in the mitochondria in a long, multistep process that produces roughly 36 ATP.

Question 51.
What is anaerobic res-piration?
Answer:
A form of incomplete intracellular breakdown of sugar or other organic compounds in the absence of oxygen that releases energy.

Question 52.
What is ATP?
Answer:
ATP is Adenosine triphosphate. It is the energy currency of life. ATP is a high- energy molecule found in every cell. Its job is to store and supply the cell with needed energy.

Question 53.
Expand NADP.
Answer:
NADP. Nicotinamide Adenine Dinucleotide.

Question 54.
Name three animals which respire through skin.
Answer:

1. Earthworm
2. Leech
3. Frog.

Question 55.
Where does Krebs cycle occur in the body?
Answer:
Krebs cycle is completed in mitochondria of cells.

Question 56.
What is hypoxia?
Answer:
Hypoxia is a condition of shortage of oxygen in the body due to strangulation on cyanide poisoning.

Question 57.
Name the respiratory sub-strate.
Answer:
Glucose.

Question 58.
What is the end product of aerobic respiration?
Answer:
Carbon dioxide and water.

Question 59.
What is fermentation?
Answer:
Incomplete breakdown of glucose in the absence of oxygen in microbes such as bacteria and yeast. It forms CO2₂, ethanol and energy is released in small amount.

Question 60.
Man breaths how many times per minute?
Answer:
12-15 times.

Question 61.
What are the functions of ATP?
Answer:
ATP provide energy for all metabolic reactions in the body such as movements, synthesis, cell division.

Question 62.
What is bark?
Answer:
The tissue ontside the outer most covering of the stem or root is called bark.

Question 63.
Name the tissue which transport food in plants.
Answer:
Phloem.

Question 64.
What is xylem?
Answer:
Xylem is a complex tissue which transport water and minerals from roots to other parts of the plant.

Question 65.
Name two substances which enter the root through the root hairs.
Answer:

1. Water
2. Soluble minerals from soil.

Question 66.
What is ascent of sap?
Answer:
The process by which water absorbed by the root is carried to aerial parts of plant is called ascent of sap.

Question 67.
Name the transport tissue of body.
Answer:
Blood and lymph.

Question 68.
Name the three types of blood vessels.
Answer:

1. Arteries
2. Veins
3. Capillaries.

Question 69.
List types of circulation in human body.
Answer:
Double circulation involving pulmonary circulation and systemic circulation.

Question 70.
Name the fluid medium of blood.
Answer:
Plasma.

Question 71.
Why is the S-A node called pace-maker of the heart?
Answer:
S-A node, being self-excitatory, initiates a wave of contraction in the heart.

Question 72.
Name the organs which play role in circulation of blood.
Answer:
Heart. It is a muscular, pumping organ. It pumps the blood in the body.

Question 73.
Name the types of cells which destroy harmful bacteria in the body.
Answer:
White blood corpuscles (W.B.C.)

Question 74.
Name the instrument used to measure blood pressure.
Answer:
Sphigmomanometer.

Question 75.
Name the artery which carry impure (deoxygenated) blood from heart to lungs.
Answer:
Pulmonary artery.

Question 76.
Expand ECG.
Answer:
Electrocardiogram.

Question 77.
Write normal blood pressure in human body.
Answer:
120/80 → Systolic = 120 and Diastolic = 80

Question 78.
Name the largest artery.
Answer:
Aorta.

Question 79.
What is excretion?
Answer:
Excretion. Elimination of nitrogenous waste materials from body is called excretion.

Question 80.
How many nephrons are present in each kidney?
Answer:
About 10 lakhs.

Question 81.
What are the excretory structures of amoeba?
Answer:
Contractile vacuole.

Question 82.
What is a malpighian body (renal corpuscle)?
Answer:
Bowman’s capsule and glomerulus.

Question 83.
Name the reservoir of urine in the body.
Answer:
Urinary bladder.

Question 84.
What is micturition?
Answer:
Act of passing out of urine from urinary bladder is called micturition.

Question 85.
Name the structures which store wastes in plants.
Answer:
Central vacuoles.

Question 86.
What are resins and gums?
Answer:
These are storage wastes of plants.

Question 87.
Define autotrophic nutrition.
Answer:
The organisms prepare their own food from raw materials like C02 and H20 in the presence of sunlight. It takes place in green plants containing chlorophyll.

Question 88.
Define heterotrophic nutrition.
Answer:
The mode of taking readymade organic food material is called heterotrophic nutrition. It may be holozoic (ingestive) or saprophytic and parasitic (absorptive).

Multiple Choice Questions

Question 1.
Among the following which is a parasitic plant?
(A) Plasmodium
(B) Cuscuta
(C) Amoeba
(D) Rhizobium.
Answer:
(B) Cuscuta

Question 2.
Dark reaction and light reaction of photosynthesis takes place is:
(A) stroma and grana of chioroplast respectively
(B) grana and stroma of chioroplast respectively
(C) grana only
(D) stroma only.
Answer:
(A)stroma and grana of chioroplast respectively

Question 3.
Chemical reaction takes place during dark reaction of photosynthesis is:
(A) photo1ysi
(B) hydrolysis
(C) carbon dioxide is bonded with RUBP
(D) nitrogen fixation.
Answer:
(C) carbon dioxide is bonded with RUBP

Question 4.
Plants are green in colour because:
(A) they absorb green light only
(B) they reflect green light
(C) they absorb green light but reflect all other lights
(D) none of the above are correct.
Answer:
(B) they reflect green light.

Question 5.
The nutrition in Mucor is:
(A) parasitic
(B) autotrophic
(C) saprophytic
(D) holozoic.
Answer:
(C) saprophytic

Question 6.
In amoeba the digestion is intracellular because :
(A) amoeba is unicellular
(B) amoeba is multicellular ‘
(C) amoeba is found in pond
(D) amoeba is microscopic animal.
Answer:
(A) amoeba is unicellular

Question 7.
Which of the following has no digestive enzyme?
(A) Saliva
(B) Bile
(C) Gastric juice
(D) Intestinal juice.
Answer:
(B) Bile

Question 8.
C02 acceptor during dark reaction of photosynthesis is :
(A) RUBP
(B) PEP
(C) NADPH
(D) ATP.
Answer:
(A) RUBP

Fill in the blanks:

Question 1.
Viruses show _________ movements.
Answer:
Molecular.

Question 2.
Growth, _________ and repair and _________ are characteristics of life.
Answer:
movements, maintenance.

Question 3.
_________ is needed by living organisms for movements and maintenance.
Answer:
Energy.

Question 4.
_________ is the largest gland of body.
Answer:
Liver

Question 5.
_________ and are the raw materials for photosynthesis.
Answer:
C02 and H20.

Question 6.
RBC transport _________ in the body.
Answer:
Oxygen.

Question 7.
Xylem and _________ are the main conducting tissues in plants.
Answer:
Phloem.

Question 8.
Translocation of food takes place through _________ of phloem.
Answer:
Sieve tubes.

Punjab State Board PSEB 10th Class Science Important Questions Chapter 5 Periodic Classification of Elements Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 5 Periodic Classification of Elements

Long Answer Type Questions

Question 1.
What do you understand by Dobereiner’s triads? Give some examples to support it.
Answer:
In 1817, a German Chemist, Dobereiner, gave a classification in which the similar elements were arranged in groups of three called Triads. The arrangement was such that the atomic mass of the middle element was almost the average of the atomic masses of the first and third elements. For example, if A, B and C are the elements present in the triad, then

Atomic mass of B =\(\frac{\text { Atomic mass of } \mathrm{A}+\text { Atomic mass of } \mathrm{C}}{2}\)

Examples of triads.
A few examples of triads are listed as given ahead :
1. Lithium, Sodium. Potassium
Atomic mass of Lithium (Li) = 7
Atomic mass of Potassium (K) = 39
Atomic mass of Sodium (Na) = \(\frac{39+7}{2}\) = 23
Actual atomic mass of sodium = 23

This group of triads is called Alkali Metal Group. All the elements present are metals, have valency equal to one (1) and dissolve in water to form soluble hydroxides called alkalis.

2. Calcium, Strontium, Barium
Atomic mass of Calcium (Ca) = 40
Atomic mass of Barium (Ba) = 137
Atomic mass of Strontium (Sr) = \(\frac{137+40}{2}=\frac{177}{2}\) = 88.5
Actual atomic mass of strontium = 88

This group of triads is called Alkaline Earth Metals Group. All the elements present are metals, have valency equal to two (2) and their oxides dissolve in water to form hydroxides which are alkaline in nature.

Question 2.
(a) What was Dobereiner’s basis of classifying elements?
Answer:
Dobereiner gave a classification in which the elements were arranged in a group of three elements called triads. The arrangement was such that the atomic masses of the middle elements were almost the average of the atomic masses of the first and third elements.

(b) What is the basis of classification of elements according to Mendeleev?
Answer:
The major contribution in the classification of the elements is by Mendeleev, a Russian chemist. He studied in detail the properties of the elements and made a very important observation. He stated that when elements are arranged in order of increasing atomic masses, the elements with similar properties recur after a definite gap. He based his classification of law called Mendeleev’s Periodic Law. The law may be stated as:

Physical and chemical properties of the elements are periodic function of their atomic weights or atomic masses.

Question 3.
Give a brief discussion of the Mendeleev’s classification of the elements.
Answer:
Mendeleev’s classification of the elements is based upon the Mendeleev’s periodic law. The law helped him to develop a table called Mendeleev’s Periodic Table. The table has been divided into vertical columns which are called Groups and horizontal rows which are known as Periods.

These are briefly discussed as follows :
1. Groups: These are the vertical rows. There are in all eight groups. The elements present in first seven groups are called Normal Elements. The elements present in group VIII are called the Transition Elements. Each group (I to VII) has been further divided into sub-groups which are called A and B. The inert gas or noble gas elements (He, Ne, Ar, Kr, Xe) were not known at that time. Therefore, they were not shown in the table. All the elements placed in a group have the same valency. Ail the elements present in a sub-group have the similar properties. For example, group I-B includes element Cu (Copper), Ag (Silver) and Au (Gold). They have similar properties.

2. Periods: In the periodic table horizontal rows are called periods. There were in all six periods in the original periodic table. The seventh period was added later on and this is not shown in the periodic table. The properties of the elements present in a period change systematically. For example, in every period, the first element is a typical metal. As we move from left to right, the metallic character gradually decreases and non- metallic character increases. For example, in period 2, the first element Li (Lithium) is a metal while the last element F (Fluorine) is a non-metal. The Mendeleev’s Periodic Table is shown below :

Mendeleev’S Periodic Table

Question 4.
(a) Why do we classify elements?
Answer:
To simplify and systematize the study of known elements.

(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
Answer:

1. Mendeleev arranged the elements in order of increasing atomic masses.
2. Mendeleev considered the compounds formed by the elements oxygen and hydrogen.

(c) Why did Mendeleev leave some gaps in his Periodic Table?
Answer:
For the discovery of new elements.

(d) In Mendeleev’s Periodic Table, why was there no mention of Noble gases like7 Helium, Neon and Argon?
Answer:
Because noble gases were not known at that time.

(e) Would you place the two isotopes of chlorine, Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
Answer:
In the same slot because Cl-35 and Cl-37 have same chemical properties.

Question 5.
How did Mendeleev’s Periodic Table help in the discovery of new elements?
Answer:
When Mendeleev gave the periodic table, only 63 elements were known. The classification was based on two major properties :

• Elements are arranged in order of increasing atomic masses.
• Elements present in a group have similar properties.

Many elements were not known at the time the periodic table was given. Therefore, Mendeleev left gaps for these elements in the periodic table. But the properties of these elements could be predicted. For example, let us suppose that Rb (Rubidium) a member of group IA was not known when Mendeleev framed the periodic table. But its properties could be predicted. It was expected to be a metal with valency equal to 1. It was expected to be soluble in water to form a soluble hydroxide RbOH which is an alkali. This helped in the discovery of the element. In this manner, a number of elements could be discovered.

Question 6.
Discuss some major merits of the Mendeleev’s Periodic Table.
Answer:
Merits of Mendeleev’s Periodic Table
Mendeleev’s periodic table was the first proper systematic classification of the elements. The important merits of the table are listed as follows :
1. Systematic study of elements. With the classification of elements into groups and periods, their study became quite systematic. For example, if the properties of one particular element in a group are known, those of the other elements could be predicted. Actually, elements placed in a group are expected to show similar characteristics.

2. Correction of wrong atomic masses. The periodic table helped in correcting the atomic masses of some of the elements because the elements were arranged in order of their increasing atomic masses.

3. Prediction of new elements. At the time Mendeleev gave the periodic table, only 63 elements were known. While arranging these elements in groups and periods, certain gaps were left. These gaps represented some undiscovered elements. But the properties of these unknown elements could be predicted from their positions in the respective groups. This helped, later on, to discover these elements.

Question 7.
On the basis of Mendeleev’s Periodic Table given following, answer the questions that follow the table :

(a) Name the element which is in
(i) 1st group and 3rd period
Answer:
Sodium

(ii) VII group and 2nd period.
Answer:
Fluorine

(b) Suggest the formula for the following :
(i) oxide of nitrogen
Answer:
N₂O₅

(ii) hydride of oxygen.
Answer:
H₂O.

(c) In group VIII of the Periodic Table, why does cobalt with atomic mass 58.93 appear before nickel having atomic mass 58.71?
Answer:
Because the elements with similar properties could be grouped together.

(d) Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his Periodic Table?
Answer:
Scandium and Germanium.

(e) Using atomic masses of Li, Na and K, find the average atomic mass of Li and K and compare it with the atomic mass of Na. State the conclusion drawn from this activity.
Answer:
Average atomic mass of Li and K = \(\frac{6.939+39.102}{2}=\frac{46.04}{2}\) = 23.02
Atomic mass of Na = 22.99
Hence Atomic mass of Na = Average of atomic masses of Li and K = \(\frac{46.04}{2}\) = 23.02

Question 8.
Point out the major defects in Mendeleev’s Periodic Table.
Answer:
Defects in Mendeleev’s Periodic Table:
Mendeleev’s periodic table was quite helpful in the classification of the elements.

But it had certain defects also. These are discussed as follows :
1. Position of hydrogen. Hydrogen was placed at the top of group LA. It is a non-metal where all other elements included in the group are metals.

2. Position of isotopes. The periodic table is based on the basis of the atomic masses of the elements and the elements with different atomic masses must be given separate places in the table. If this is correct, all the isotopes of an element must be allotted separate positions. For example, there are three isotopes for hydrogen and they must be given three separate places in the table. But only one position for hydrogen has been given.

3. Wrong order of atomic masses of some elements. In the table, the elements are arranged in order of increasing atomic masses. This means that the element with higher atomic mass must be placed after the element with the lower atomic mass. But in the table, there are some anomalies. For example, Co (Cobalt) with atomic mass 58-9 should be placed after Ni (Nickel) with atomic mass 58-7. But it has been placed before nickel.

4. Elements with similar properties placed in different groups. In the periodic table, it has been found that the elements with similar properties are placed in different groups. For example, copper and mercury have many common properties. But copper has been placed in group I B and mercury in group II B.

5. No similarity in the elements placed in sub-groups. The elements present in different sub-groups of the same group are expected to have common properties. But these are quite different. For example, elements in group I A are very soft and reactive metals but elements in group IB are hard and less reactive in nature.

6. No explanation for the cause of periodicity. Mendeleev was not in a position to explain why the elements included in a group show similar properties.

Question 9.
Give a brief description of Long Form of Periodic Table.
Answer:
The Long form of periodic table has been formed by arranging the elements in order of increasing atomic numbers. It is based upon Modern periodic law which states that the properties of the elements are the periodic function of their atomic numbers. Just as in case of the Mendeleev’s table, this periodic table has also been divided into Periods and Groups.
(A) Groups
These are the vertical columns. In all, there are eighteen groups in the table. The details of the groups are as follows :

Long Form of Periodic Table of Modern Periodic Table

• Group 1: The elements present in group I or 1 are called Alkali Metals.
• Group 2: The elements which are present in group IIA or 2 are called Alkaline Earth Metals.
• Groups 13 to Group 18: There are in all six groups. The Groups 13 to 16 are named after the first element present in the family. For example, Group IIIA or 13 is called Boron Family because first member is boron.
• Group 17 consists of a family called Halogen Family.
• The group 18 is also called zero group because the elements have zero valency. These elements are ail gases. They have very little tendency to take part in chemical combination. These are also called Noble Gases.

In the latest Long Form of Periodic Table, groups of Alkali metals and Alkaline erttH metals are given numbers 1 and 2. The transition of elements are numbered from its,2 The non-metals are included in groups 13 to 18.

Group No.	Name of Family
Group 13	Boron Family
Group 14	Carbon Family
Group 15	Nitrogen Family
Group 16	Oxygen Family
Group 17	Halogens
Group 18 or zero group	Noble Gases

• Group 3 to Group 12: There are in all ten groups. These are all metals and are called Transition elements. When we go down each group, the metallic character further increases.
• Group 3: Group 3 also includes fourteen elements belonging to Lanthanide family. These are called Lanthanides because they start after Lanthanum (La) with Z = 57. These are present in the 6th period as shown in the table.
• It also includes another fourteen elements called Actinides. These are present in 7th period. These are so called as they come after Actinium (Ac) with Z = 89. These are placed at the bottom of the table for convenience.

(B) Periods
Periods are the horizontal rows which are present in the Long Form of Periodic Table. Different periods have different number of elements and their atomic numbers are continuous. There are in all seven periods. The seventh period is still incomplete. The number of elements which are included in each period are given below :

Period	No. of elements	Name of the Period
1	2	Shortest Period
2	8	Short Period
3	8	Short Period
4	18	Long Period
5	18	Long Period
6	32	Longest Period
7	20	Incomplete Period

Question 10.
What is periodicity? What is the cause of periodicity?
Answer:
Periodicity may be defined as the repetition of the similar properties of the elements placed in a group and separated by definite gaps of atomic numbers (8, 8, 18, 18, 32).

Cause of Periodicity. The properties of the elements, particularly the chemical properties, are linked with number of electrons present in the outermost shell of their atoms which is also called Valence shell. Elements with similar valence shell electronic configurations are expected to have similar properties.

It may be noted that all the elements which are present in a group have the same number of electrons in the valence shells of their atoms. In other words, the same valence shell electronic arrangement gets repeated after definite gaps of atomic numbers (8, 8, 18, 18, 32). Therefore, the elements placed in a group show similar properties.

Example, Let us write the electronic distribution of the first four members of the alkali metals present in group I.

All the four elements have one electron each in the valence shell of their atoms. They have, therefore, similar properties.

Question 11.
(a) What were the two major shortcomings of Mendeleev’s periodic table? How have these been removed in the modern periodic table?
Answer:
The shortcomings of Mendeleev’s periodic table are :

• Isotopes of an element find different positions in periodic table.
• Some chemically similar elements have been separated and some dissimilar elements are placed together.

In these Modern Periodic Table
Modern Table

• Isotopes of an element occupy the same position because they have same atomic number.
• The similar elements are grouped together and dissimilar elements are separated.

(b) Two elements X and Y have atomic numbers 12 and 16 respectively. Write the electronic configuration for these elements. To which period of the modern periodic table do these two elements belong? What type of bond will be formed between them and why?
Answer:

Element	Electronic Configuration	Period
X12	2, 8, 2	3rd
Y16	2, 8, 6	3rd

They will form ionic bonds because two electrons are transferred from X to Y so that they get their octets complete :

Question 12.
Why is Long Form of Periodic Table regarded better than Mendeleev’s Periodic Table?
Or
How could Modern Periodic Table remove various anomalies of Mendeleev’s Periodic Table?
Answer:
Long Form of Periodic Table is regarded better than the Mendeleev’s periodic table due to the following reasons:

• It is based upon atomic number which is considered better than the atomic mass because the properties of the elements are related to the atomic number.
• It explains why the elements placed in a group show similar properties but Mendeleev’s Periodic Table gives no explanation for the same.
• All groups in the Periodic Table are independent groups and there are no sub¬groups as in Mendeleev’s Periodic Table.
• Many defects in the Mendeleev’s Periodic Table have been removed.
• There is no confusion regarding the position of isotopes because all the isotopes of an element have the same atomic number.
• The periodic table is more systematic than the Mendeleev’s table and is easy to remember.

Question 13.
The following tables shows the position of six elements A, B, C, D, E and F in the periodic table.

Using the above table answer the following questions :
(a) Which element will form only covalent compounds?
Answer:
E

(b) Which element is a metal with valency 2?
Answer:
D

(c) Which element is non-metal with valency of 3?
Answer:
B

(d) Out of D and E, which one has a bigger atomic radius and why?
Answer:
D

(e) Write a common name for the family of elements C and F,
Answer:
The noble gases.

Question 14.
The question refers to the elements of the periodic table with atomic number from 3 to 18.

(a) Which of these :
(i) is/are noble gas?
Answer:
H, P

(ii) is it a halogen?
Answer:
G, O

(iii) is an alkali metal?
Answer:
A, I

(iv) is it a metal with valency 2?
Answer:
A, I

(b) Write the electronic arrangement of G.
Answer:
G has the electronic configuration = 2, 7

(c) If A combines with F, what would be the formula of resulting compound?
Answer:

Short Answer Type Questions

Question 1.
Atomic number is considered to be a more appropriate parameter than atomic mass classification of elements in a periodic table. Why?
How does atomic size of elements vary on moving from
(i) Left to right in a period.
(ii) from top to bottom in a group.
Give reasons for your answers.
Answer:

• This is because atomic number is a more fundamental property of an atom.
• As we move from left to right along a period atomic radius decreases due to increase in effective nuclear charge.
• As we move from top to bottom in a group, atomic radius increases. This is due to addition of new electronic shells.

Question 2.
Define periodic law. Why was it necessary to change the basis of classification from atomic masses to atomic numbers?
Answer:
Periodic Law: The properties of elements are a periodic function of their atomic numbers. It was necessary to change the basis of classification from atomic masses to atomic numbers because atomic number and not atomic mass is the fundamental property of an element.

Question 3.
What do you understand by the term periodicity? Do the properties of two elements placed in a group the same? Illustrate.
Answer:
The repetition of the similar properties of the elements placed in a group and separated by definite gaps of atomic numbers (8, 8, 18, 18, 32) is called periodicity. The elements placed in a group show similar properties, e.g. consider group 1 elements.

Element	Symbol	Electronic configuration
Lithium	(3)	Li – 2, 1
Sodium	(11)	Na – 2, 8, 1
Potassium	(19)	K – 2, 8, 8, 1
Rubidium	(37)	Rb – 2, 8, 18, 8, 1
Cesium	(55)	Cs – 2, 8, 18, 18, 1
Francium	(87)	Fr – 2, 8, 18, 32, 18, 8, 1

These elements show similar properties because they have similar outer electronic configurations.

Question 4.
What was wrong with Dobereiner’s classification of elements?
Answer:
Dobereiner classified the elements in group of three in such a way that the atomic mass of the middle element was the mean of the first and the third elements. But he could not find many triads of elements. Therefore, the classification was rejected.

Question 5.
What properties do ail elements in the same column of the periodic table as boron have in common?
Answer:
The elements of Boron family in the periodic table show

• Tricovalency
• Form trihalides
• Form trioxides
• React with halogens to form halides.

Question 6.
Indicate the atomic number of elements of period 3 of Modern periodic table :
(a) non-metals
Answer:
14, 15, 16, 17

(b) elements forming negative ions.
Answer:
15, 16, 17

(c) elements with high melting points.
Answer:
11, 12, 13, 14

(d) elements forming positive ions.
Mention the atomic number only.
Answer:
11, 12, 13

Question 7.
Define atomic radius. Give its units.
Answer:
Atomic radius. It may be defined as the distance between the centre of nucleus and the outermost shell of an isolated atom.

Also the atomic radius of a non-metallic element is defined as half the distance between the nuclei of two atoms bound by a single covalent bond.
Units = Å or pm (picometre)
e.g. atomic radius of hydrogen atom = 37 pm.

Question 8.
How does atomic radius vary down a group and along a period?
Answer:
Variation in a group. The atomic radius generally increases from top to bottom in a group due to the addition of a new shell.
Variation along a period. The atomic radius decreases on moving from left to right due to the increase in nuclear charge.

Question 9.
Write down the electronic configuration of elements with atomic numbers 2, 14, 17, 19. Indicate the group of the periodic table to which they belong.
Answer:
The information is being given in a tabular form.

Atomic number	Electronic configuration K L M N	Group
2	2	18
14	2, 8, 4	14
17	2, 8, 7	17
19	2, 8, 8, 1	1

Question 10.
Locate the following group in the periodic table :
(a) Alkali metals
Answer:
Alkali metals: Group 1 or IA

(b) Halogens
Answer:
Halogens: Group 17 or VIIA

(c) Alkaline earth metals
Answer:
Alkaline earth metals: Group 2 or IIA

(d) Noble gases.
Answer:
Noble gases: Group 18 or zero

Question 11.
What properties do the elements in the same vertical column of the periodic table as fluorine have in common?
Answer:
These are :

• They form diatomic molecules F₂, Cl₂, Br₂ I₂
• They are non-metals.
• They show a valency of one.

Question 12.
Write the chemical electronic configuration of nitrogen (N = 7) and phosphorous (P = 15).
Answer:

Question 13.
(i) Name the members of the alkaline earth family.
Answer:
The members of the alkaline earth family are :
Be, Mg, Ca, Sr, Ba, Ra.

(ii) To which group do they belong?
Answer:
They belong to group 2.

(iii) Which member is radioactive in nature?
Answer:
The radioactive member in them is Radium (Ra).

(iv) Which member is the least reactive?
Answer:
The least reactive member of the family is Beryllium (Be).

Question 14.
Why are the members of group 1 called alkali metals?
Answer:
The members of group 1 are called alkali metals because all of them are water soluble. They react with water to form soluble hydroxides. The soluble hydroxides of the metals are called alkalies.

Question 15.
An atom has the electronic configuration 2, 8, 7.
(a) What is the atomic number of this element?
Answer:
The atomic number of the element = Total number of electrons
= 2 + 8 + 7 = 17

(b) To which of the following elements would it be chemically similar? (atomic numbers are given) N (7), F (9), P (15), Ar (18).
Answer:
The electronic configurations of given atom and N, F, P and Ar are.

Atom	Electronic configuration
	K	L	M
	2	8	7
N	2	5
F	2	7
P	2	8	5
Ar	2	8	8

Since F has same number of electrons in the outermost shell as the given atom. Hence, the given atom is chemically similar to F.

Question 16.
What physical and chemical properties of elements were used by Mendeleev in creating his periodic table? List two observations which posed a challenge to Mendeleev’s Periodic Law.
Answer:
He selected the compounds of the elements with oxygen and hydrogen. He gave a table based upon atomic weights of the elements.

Limitations of Mendeleev’s Classification

• The position of hydrogen was uncertain.
• The isotopes of elements were not given proper positions in the periodic table.

Question 17.
(a) What are amphoteric oxides? Choose the amphoteric oxides from amongst the following oxides :
Na₂O, ZnO, Al₂O₃, CO₂, HaO
Answer:
The oxides which can react both with acids as well as bases to produce salts and water.

(b) Why is it that non-metals do not displace hydrogen from dilute acids?
Answer:
This is because non-metals cannot lose electrons and cannot reduce H⁺ ions from acid to H₂.

Question 18.
What are noble gas elements? Why are they so called?
Answer:
Noble gas elements are the. elemehts present in group 18 of the periodic table which is also called zero group, It means that the valency of the elements is zero. Actually, whereas the first member helium has two electrons in its only shell, the atoms of the remaining elements (Neon, Argon, Krypton, Xenon and Radon) have eight electrons in their outermost shells. They do not have any tendency to combine with atoms of other elements. Hence, they show zero valency. These are also called noble gases because they do not take part in chemical combination.

Question 19.
How is metallic character of an element defined? How does the metallic character of the elements change in a group?
Answer:
The metallic character of an element may be expressed in terms of its tendency to lose electrons and to form positive ion.
M (Element) → M⁺ + e^–

In a group the metallic character increases’ downwards. For example, among the elements of group 2, Beryllium (Be) is the least metallic. At the same time, radium (Ra) which is the last element is maximum metallic in nature.

Question 20.
Why do the elements present in a group show similar chemical properties?
Answer:
The properties of the elements, particularly the chemical properties are related to valence shell electronic distribution. The elements with the same valence shell electronic distribution have the similar chemical properties. For example, the members, of alkaline earth metal family (Group 2) have two electrons in the valence shell of their atoms. They therefore, show similar chemical properties.

Question 21.
How does the reactivity of the metals vary in a group?
Answer:
In a group, containing metals, the reactivity increases down the group. For example, in the metals of group 1 (Alkali metals), Lithium reacts with water very slowly. Sodium is more reactive and potassium is. still more reactive than sodium.

Question 22.
Name the elements present in the second period. Give their electronic configuration.
Answer:
The second period of the Long Form of Periodic Table has eight elements. The first element is Lithium and the last element is Neon. The electronic configuration of the elements are given below:

Question 23.
Why do not the elements present in a period show same valency?
Answer:
The valency of the element is related to the number of electrons in the outermost energy shell of its atom. Since the elements present in a period have different number of valence electrons or outermost electrons, they show different valencies.

Question 24.
The metallic character of the elements in a period decreases from left to the right. Justify.
Answer:
In every period, as we move from left to right, the metallic character of the elements decreases gradually. This is shown with the elements present in the third period.

Question 25.
Give symbols for :
(a) a metal belonging to second group of the periodic table.
Answer:
The metal belonging to second group is calcium (Ca).

(b) a metal belonging to the third group of the periodic table.
Answer:
The metal belonging to third group is aluminium (Al).

(c) two non-metals belonging to the halogen family.
Answer:
The two non-metals of halogen family are fluorine (F) and chlorine (Cl).

Question 26.
Write electronic structures of:
(i) Potassium
(ii) Lithium
(iii) Fluorine.
Answer:
The electronic configurations of the atoms are given below :

Question 27.
Name two other elements which are in the same family as
(i) carbon
Answer:
Carbon belongs to the group 16. Two other elements are silicon (Si) and germanium (Ge).

(ii) fluorine
Answer:
Fluorine belongs to group 17. Two other elements are chlorine (Cl) and bromine (Br).

(iii) sodium.
Answer:
Sodium belongs to group 1. Two other elements are lithium (Li) and potassium (K).

Question 28.
Carbon (atomic number 6) and silicon (atomic number 14) are elements in the same group of the periodic table. Give the electronic arrangements of the carbon and silicon atoms and state the groups in which these elements occur.
Answer:
The required information may be given in a tabular form as follows :

Element	Atomic no.	Electronic arrangement	Group
Carbon (C)	6	2, 4	14
Silicon (Si)	14	2, 8, 4	14

Question 29.
Sodium and aluminium have atomic numbers of 11 and 13 respectively. They are separated by one element in the periodic table and have valencies of 1 and 3 respectively. Chlorine and potassium are also separated by one element in the periodic table (their atomic numbers are 17 and 19 respectively) and yet both have valency of one. Explain your answer.
Answer:
Sodium and aluminium: The electronic configurations of the elements are given below :
Sodium (Na) = 2, 8, 1
Aluminium (Al) = 2, 8, 3

The valency in this case is given by the number of valence electrons. Therefore, the valency of sodium is 1 and that of aluminium is 3.

Chlorine and potassium: The electronic configurations of the elements are given below :
Chlorine (Cl) = 2, 8, 7
Potassium (K) = 2, 8, 1

Question 30.
Give the atomic number and electronic distribution of:
(i) The third alkali metal
Answer:
Potassium (19) 2, 8, 8, 1

(ii) The second alkaline earth metal
Answer:
Magnesium (12) 2, 8, 2

(iii) The first halogen
Answer:
Fluorine (9) 2, 7

(iv) The second noble gas.
Answer:
Neon (10) 2, 8.

Question 31.
Observe the following elements in the Modern Periodic Table.

Name the elements A, B, C and D. Also indicate noble gas
Answer:
(A) Lithium
(B) Chlorine
(C) Neon
(D) Potassium C is a noble gas

Question 32.
Match the following :

(a) Fluorine	(i) Metalloid
(b) Neon	(ii) Halogen
(c) Sodium	(iii) Noble gas
(d) Arsenic	(iv) Alkali metal

Answer:

(a) Fluorine	(ii) Halogen
(b) Neon	(iii) Noble gas
(c) Sodium	(iv) Alkali metal
(d) Arsenic	(i) Metalloid

Question 33.
How many electrons can be present in the valence shells of metal atoms and non-metal atoms?
Answer:
Metal atoms have 1, 2 or 3 electrons in their valence shells whereas non-metal atoms have 4 to 7 electrons in their valence shells.

Question 34.
How are the various groups of the Modern Periodic Table designated according to the IUPAC system and old system?
Answer:
The designations of various groups of the Modern periodic table are :

Question 35.
What are the uses of Modern Periodic Table?
Answer:

• Systematic study of the elements. In the periodic table, the elements with similar properties are placed together in the same group. If we know the properties of one element of the group, the properties of other elements belonging to the same group can be predicted. Thus, there is no need to study the properties of all the elements.
• Properties of an element can be predicted from the position of the element in the periodic table. For example, if the element belongs to group IA or IIA it is likely to be a reactive metal, and if it belongs to group VII A it is likely to be a reactive non-metal.
• It has led to the discovery of many new elements.

Very Short Answer Type Questions

Question 1.
How many elements have been discovered so far?
Answer:
114.

Question 2.
How are elements classified?
Answer:
The elements have been classified on the basis of their properties.

Question 3.
Why are group IA elements called alkali metals?
Answer:
This is because all these elements are metals and their oxides and hydroxides give alkaline solutions in water.

Question 4.
What is the basis of Modern Periodic table?
Answer:
It is based upon Modern Periodic law.

Question 5.
Name the family to which halogens belongs?
Answer:
Halogen family.

Question 6.
Name the second elements of group 14.
Answer:
Silicon.

Question 7.
How many valence electrons and present in halogen elements?
Answer:
Seven.

Question 8.
How many elements are present in 4th period?
Answer:
18.

Question 9.
How many electrons are present in Mg²⁺ ion?
Answer:
Ten.

Question 10.
Out of Na and Mg which was larger size?
Answer:
Na

Question 11.
What is the valency of nitrogen?
Answer:
Three.

Question 12.
Out of Na and K which is more reactive?
Answer:
Sodium (Na).

Question 13.
Name the group number of halogen family.
Answer:
Group 17 (or VII-A).

Question 14.
Name the last element of third period?
Answer:
Argon.

Question 15.
What is Dobereiner’s Triad?
Answer:
A group of three elements having similar properties is called Dobereiner’s Triad.

Question 16.
A, B and constitute the Dobereiner s Traid. Atomic mass of A and C are 7 and 23 respectively. Calculate atomic mass of B.
Answer:
\(\frac{7+23}{2}=\frac{30}{2}\) = 15

Question 17.
Name the elements discovered after Mendeleev’s Periodic Table?
Answer:
Scandium (Se), Gallium (Ga), Germanium (Ge) etc.

Question 18.
Name the groups and periods in Mendeleev’s Periodic Table?
Answer:
8 groups and 7 periods.

Question 19.
How does atomic radii as we move from left along a period in the Periodic Table?
Answer:
It decreases.

Question 20.
An element has the electronic configuration 2, 8, 3. What is its group number in Modern Periodic Table?
Answer:
Group 13.

Question 21.
Give the basis of Dobereiner’s classification.
Answer:
Doberenier Triads.

Question 22.
Give the characteristics of Dobereiner’s Triads.
Answer:
The atomic mass of the central element is the average of masses of the other two elements.

Question 23.
What is the drawback of Doberenier’s Triads?
Answer:
All the known elements could be grouped into Triads.

Question 24.
There are three alements A, B and C. The atomic masses of A and C are 7 and 39. What is the atomic mass of B on the bais of Dobereiner’s Traids?
Answer:
Atomic mass of B = \(\frac{7+39}{2}\) = 23.

Question 25.
There are three elements X, Y, Z. Atomic masses of X and Z are 35.5 and 127. What will be atomic mass of Y on the basis of Dobereiner’s Traids?
Answer:
Atomic mass of Y
\(\frac{35.5+127}{2}=\frac{162.5}{2}\) = 81.25

Question 26.
Write Newland’s Law of Octaves for classification of elements.
Answer:
When the elements are arranged in order of increasing atomic masses, eighth elements has properties similar to the first element.

Question 27.
How many element were classified by Newland.
Answer:
Upto mass number 40.

Question 28.
Indicate the group number and period number of P in the modern Periodic Table.
Answer:
Group-15, Period-3.

Question 29.
An element has the electronic configuration 2, 8, 8, 2. Indicate its group and Period in the Modern Periodic Table.
Answer:
Group-12, Period-4.

Question 30.
An element M is in the group 13 of Modern Periodic Table write the formula of its oxide.
Answer:
M₂O₃.

Question 31.
Give the groups and periods in the Modern Periodic Table.
Answer:
Group-18, Periods-7.

Question 32.
Give the electronic configuration of ₁₇Cl³⁵. Also indicate its position in the Periodic Table.
Answer:
Electronic configuation of ₁₇Cl³⁵ = 2, 8, 7
Period number = 3
Group number =17. (VII A)

Question 33.
Give the name and electronic configuation of element with atomic number 9.
Answer:
Fluorine and it has the electronic configuation = 2, 7.

Question 34.
What is Modern Periodic Law?
Answer:
It states that the properties of the elements are the periodic functions of their atomic numbers.

Question 35.
Who gave Newland’s Law of Octaves.
Answer:
Newland.

Question 36.
Define Mendeleev’s periodic law.
Answer:
It states that the properties of the elements are the periodic functions of their atomic masses.

Question 37.
What is the basis of Mendeleev’s Modern Table?
Answer:
It is based upon Mendeleev periodic law and in this table the elements are arranged in order of increasing atomic masses.

Question 38.
How many groups are present in Mendeleev’s Period Table.
Answer:
Eight.

Question 39.
Name the next elements after P in Modern Periodic Table.
Answer:
Sulphur (S).

Question 40.
Give the group number of nitrogen and phosphorus.
Answer:
They belong to group number 15.

Question 41.
Out of Mg and Al which is more metallic?
Answer:
Mg.

Question 42.
Out of Be, Mg, Ca, Al which does not belong to same group?
Answer:
Al.

Question 43.
In which group noble gases are present?
Answer:
Group 18 or group zero.

Question 44.
Na and S are present in the third period of Modern Periodic Table. Which is more metallic and why?
Answer:
Na is more metallic due to larger size than S.

Question 45.
What is metallic character?
Answer:
It is the tendency of an atom of the element to form positive ions by losing electrons.

Question 46.
What is the trend in metallic character on moving from left to right along a period?
Answer:
It decreases.

Multiple Choice Questions:

Question 1.
Who gave Law of octaves?
(A) Newland
(B) Dobereiner
(C) Mendeleef
(D) Lother Mayer.
Answer:
(A) Newland

Question 2.
In Mendeleef’s periodic table which element was discovered in the gap between Boron and Aluminium ?
(A) Na
(B) Ca
(C) Ga
(D) Ba.
Answer:
(C) Ga

Question 3.
According to Mendeleef’s periodic law, the elements are arranged in order of A increasing:
(A) Atomic numbers
(B) Decreasing atomic number
(C) Increasing atomic masses
(D) Decreasing atomic masses.
Answer:
(C) Increasing atomic masses

Question 4.
Which element occupied gap left in Mendeleers periodic table?
(A) Germanium
(B) chlorine
(C) Oxygen
(D) Silicon.
Answer:
(A) Germanium

Question 5.
An element has the electronic configuration 2, 8, 2. It is present in group:
(A) 2
(B) is
(C) 8
(D) 10.
Answer:
(A) 2

Question 6.
Which element shows metallic character?
(A) 2, 8, 2
(B) 2, 8, 4
(C) 2, 8, 8
(D) 2, 7.
Answer:
(A) 2, 8, 2

Question 7.
Which shell is largest shell?
(A) K
(B)L
(C) M
(D) N.
Answer:
(D) N

Fill in the blanks :

Question 1.
Out of Na and Mg, ______ has bigger size.
Answer:
Na.

Question 2.
Number of elements known in Mendeleefs periodic table were ______
Answer:
63.

Question 3.
Oxygen and sulphur belong to same ______
Answer:
group.

Question 4.
The elements of group 17 are called ______
Answer:
halogens.

Question 5.
The valency of the members of noble gas family is ______
Answer:
zero.

Question 6.
The halogens belong to group ______
Answer:
17.

Punjab State Board PSEB 10th Class Science Important Questions Chapter 4 Carbon and its Compounds Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 4 Carbon and its Compounds

Long Answer Type Questions

Question 1.
What is allotropy? Name the allotropes of carbon. Are they chemically same? Compare their physical properties.
Answer:
Allotropy: The phenomenon of existence of two or more different physical forms of the same chemical element, with same chemical properties is called allotropy.

Allotropes of carbon

• Diamond
• Graphite

Similarity in chemical composition:
If both the allotropes in equal amount are heated in air then both will release same amount of carbon dioxide and will not leave any residue. Therefore this proves that both are same in chemical composition.

Comparison of Physical Properties

Property	Diamond	Graphite
1. Appearance	Transparent	Black, shiny
2. Hardness	Very hard	Soft, slippery/ smooth in touch
3. Heat conductivity	Very less	Medium conductor
4. Electric conductivity	Bad conductor	Good conductor
5. Density (kg/m3)	3 – 510	2 – 250
6. Purity	Purest	Less pure than diamond
7. Melting point	3500°C	3000°C
8. Uses/Applications	Jewellery, drilling purpose Lubricants.	Drycells, Electric Arcs, Pencils, Lead,

Question 2.
What is covalent bond? Write its properties.
Answer:
The chemical bond formed by sharing of electrons between atoms of same or different non-metal elements is known as covalent bond.

Properties of Covalent bond/bonds.

• They hax e strong bonds within molecules but their inter molecular bond is weak.
• They have low boiling points.
• They have low melting points.
• Their compounds are bad conductors of electricity.

Question 3.
(a) Why does carbon form largest number of compounds?
Answer:
This is due to its tetracovalency and catenation.

(b) Why are some of these called saturated and other unsaturated compounds?
Answer:
The compounds containing C – C single bond are called saturated compounds and the compound containing

bonds are called unsaturated compounds.

(c) Which of these two is more reactive?
Answer:
Unsaturated compounds are more reactive than saturated compounds.

(d) Write the names of the compounds
(i) CH₃ – CH₂ – Br
Answer:

Answer:

Question 4.
Write about nomenclature of carbon compounds.
Answer:
The names of compounds in a homologous series are based on the name of basic carbon chain modified by a prefix’ ‘phrase before’ or ‘suffix’ ‘phrase after’ indicating the nature of the functional group. For example, the names of various alcohols are methanol, ethanol, propanol and butanol.

Naming of carbon compound can be done by the following method :

• Identify the number of carbon atoms in the compound. A compound having three carbon atoms will have the name propane.
• In case a functional group is present, it is indicated in the name of the compound with either a ‘prefix’ or a ‘suffix’. Like chloro propane, bromo propane, propanal, propanone etc.
• If the name of functional group is to be given on the basis of suffix, the name of the carbon chain is modified by deleting the final ‘e’ and adding the appropriate suffix. For example, a chain having three carbons with a Ketone group will be given name in the following manner.
  Propane-‘e’ = propan + ‘one’ = propanone.
• If the carbon chain is unsaturated then the final ‘ane’ in the name of carbon chain is substituted by ‘ene’ or ‘yne’. For example, a three-carbon chain with a double bond would be called propene and if it has triple bond, it would be called propyne.

Question 5.
Write down the chemical properties of carbon compounds.
Answer:
The main chemical properties of carbon compounds are :
1. Burning: Carbons in all its allotropic forms burns in the presence of oxygen and produces heat, light and C02, For example :
C + O₂ → CO₂ + heat and light
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat and light
CH₃CH₂OH + 3O₂ → 2CO₂ + 3H₂O + Heat and light.
Saturated hydrocarbons burn with a clear flame whereas unsaturated hydrocarbons burn with sooty yellow flame.

2. Oxidation: Carbon compounds can easily be oxidised by burning. Alkaline potassium permanganate or acidified potassium permanganate converts alcohols into acids.

3. Addition reaction: Unsaturated hydrocarbons make saturated hydrocarbons by adding hydrogen to itself in the presence of catalysts like nickel and palladium. The reaction is commonly used in hydrogenation of vegetable oils using nickel catalyst.

Vegetable oils generally have long unsaturated carbon chain while animal fats have saturated carbon chains.

4. Substitution reaction: Saturated hydrocarbons are fairly unreactive and are inert in the presence of most reagents. However, in the presence of sunlight, chlorine gets combined with hydrocarbons in a quick reaction. Chlorine replaces very quickly the hydrogen atoms in the chemical reaction one by one due to which number of products are usually formed with the higher homologous of alkanes.

Question 6.
(a) What is an alcohol? Give two examples.
Answer:
Alcohol is a simple compound of carbon, hydrogen and oxygen. If one hydrogen atom is replaced by hydroxyl (-OH) group in alkene, alcohol is produced. General formula of alcohol is C_nH_2n+2

Examples :

• In Methane (CH₄) when hydrogen atom is replaced by hydroxyl (- OH) group, methanol (CH₃OH) is formed.
• Ethanol (C₂H₅OH) is produced with the help of ethane

(b) How is synthetic ethanol produced? Also write.
Answer:
Synthetic ethanol is prepared by reacting ethane with water in the presence of phosphoric acid (H3P04).

Properties of Ethanol :

• It is a colourless liquid with specific colour.
• Its boiling point is 351 K and melting point is 156 K.
• It is soluble in water in any proportion.
• It doesn’t show any reaction with litmus because it is neutral.
• It burns with blue flame in air to produce carbon dioxide and water.
  C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
• It reacts with oxygen or potassium dichromate (K₂Cr₂O₇) to produce ethanoic acid.
  C₂H₅OH + O₂ → CH₃COOH + H₂O
• It reacts with sodium metal.
  2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂
• It reacts with acetic acid in the presence of concentrated H₂SO₄. When this mixture is heated and poured in ice cold solution of sodium carbonate, a sweet smell is produced.

Question 7.
Give important properties of monocarboxylic acids. Also give its uses.
Or
Give important properties of ethanoic acid (Acetic acid). Also give its uses.
Answer:
Important properties of monocarboxylic acid :
1. Ethanoic acid or acetic acid is colourless liquid and is soluble in water, 5-8% solution of acetic acid in water is called vinegar.

2. Pure ethanoic acid melts at 290 K and freezes during winter in cold climates and looks like ice. Hence it is called glacial acetic acid.

3. Esterification: When an acid is heated with an alcohol in the presence of cone. H2S04, an ester is produced. This is a slow reversible reaction and is called esterification.

Esters are sweet-smelling substances.

4. Action with a base

5. Action with carbonates and bicarbonates
Ethanoic acid decomposes carbonates and bicarbonates producing salt, carbon dioxide and water.
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂ ↑
CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂ ↑

Uses of ethanoic acid :

• It is used in the manufacture of dyes, perfumes and rayon.
• It is used in the manufacture of plastics, rubber and silk industries.
• It is used as a solvent.
• It is used as a vinegar in cooking, as food dressing and for preparing pickles.
• It is used for the manufacture of chemicals like acetone, acetic anhydride, etc.
• It is used for making white lead [2PbCO₃. Pb(OH)₂]

Question 8.
Explain the following terms :
(i) Esterification
Answer:
Alcohols are treated with carboxylic acids in the presence of concentrated sulphuric acid to form ester and this process in known as esterification.

Method: Mix ethyl alcohol with acetic acid in a test tube. Few drops of concentrated sulphuric acid is added and test tube is heated mildly in hot tub of water. Instantaneously sweet smell of ester is diffused in whole room.

It is an example of esterification. Ester is used in ice-cream, cold drinks, medicines, make up etc.

(ii) Saponification
Answer:
Saponification: Breaking down of fats is called saponification.

It is performed by heating vegetable or animal oils with 40% solution of caustic soda. Fats and base react to produce soap and glycerol.

Concentrated common salt solution is added to crystallize soap from water. Soap floats on the surface of water, after cooling. Soap is extracted from water and desired colour and smell are added and is given desired shape.

(iii) Decarboxylation
Answer:
Decarboxylation: Methane is produced when sodium or potassium salt of ethanoic acid are heated with sodium hydroxide and calcium oxide in 3 : 1 ratio.

It is a useful method to prepare methane. It is known as decarboxylation because one molecule of CO₂ is removed.

(iv) Polymerization.
Answer:
Polymerization: When a large number of small molecules join together at a specific temperature and pressure to form a big molecule, this process is termed as polymerization. These small molecules are known as ‘monomer’ whereas big combined molecule is known as ‘polymer.’
For example. Molecules of ethene join together at 2000 atm pressure and 200°C to form polythene.

Question 9.
Describe a method for the preparation of soap.
Answer:
Soaps are sodium or potassium salts of higher fatty acids. When the naturally occurring esters called fats or oils are heated with NaOH solution, they undergo hydrolysis to form sodium salt of higher fatty acid (called soap) and glycerol.

Manufacture of Soap. Soap can be made easily in the laboratory. Heat fat or oil with sodium hydroxide solution. After a few minutes, and constant stirring, the oil and water layers get mixed.

Add 5-10 g of common salt to it, stir the mixture and allow’ it to cool. On cooling, pale yellow a solid forms as a cake called soap.

The same principle is used for making soap in soap industry. Some other substances like perfumes, disinfectants and medicines are added to soap to give it desired characteristics.

Example :

Question 10.
What do you understand by isomers? Explain it with an example.
Or
Write down the isomers of butane.
Answer:
Isomers. The compounds with same molecular formula but different structural formula are called isomers and the phenomenon is called isomerism. There is no change in the structure of methane, ethane, propane if the atoms of carbon and hydrogen are rearranged but in case of alkane molecule if number of carbon is more than three then more than one arrangement is possible.

In this one long carbon chain is formed and the others are branched. In case of butane the chain is linked with atleast three carbon atoms with other carbon atoms. This type of alkanes are termed as iso-alkane. In a chain having no branch, carbon atom cannot be linked with two carbon atoms. Alkanes of this type are called normal alkane (n-alkane).

Two Isomers of Butane:

Isomers of Pentane

Short Answer Type Questions

Question 1.
Explain why carbon forms mostly covalent compounds?
Answer:
Carbon has four electrons in its outermost shell. In order to get stable electronic configuration, it has to lose or gain four electrons, but it is difficult to lose or gain four electrons from energy considerations. Hence, Carbon complete its octet by sharing its valence electrons with other atoms forming covatent bonds resulting in the formation of covalent compounds.

Question 2.
In order to form large amount of carbonic compounds which major elements are used other than hydrogen and oxygen?
Answer:
The number of carbonic compounds is very large which was not possible only with the help of hydrogen and oxygen. Along with these two elements some other elements like nitrogen, sulphur, oxygen, halogens (Cl, Br, I, F) etc. also combine and because of it the caybonic compounds have crossed the number of many million. These combine together on the basis of functional groups and make new compounds.

Question 3.
‘Carbon is a unique element’, why?
Answer:
Carbon is the only known element out of all other known elements, that has got capability to make long chains. Each long chain of carbon atoms provides such a simple base with which other atoms can join by various methods resulting in the composition of various compounds.

Carbon atoms can make long chains or rings in three ways because of having catenation property.

Question 4.
Explain the structure of diamond and write why is it so hard?
Answer:
In diamond each carbon atom remains at the centre of regular tetrahedral and it remains bound with covalent bond to four carbon atoms which are situated at four corners of tetrahedral. Thus, all electrons of carbon are bound atoms and none is found in free state. So it forms a strong three-dimensional tetrahedral structure and because of it diamond is the hardest substance with very high density.

Question 5.
What are the uses of diamond?
Answer:
Uses of Diamond

• Diamond being the hardest substance is used for cutting other substances.
• Diamond because of its shine and lustre is used for making ornaments.
• It is used for drilling hard rocks.
• Sharp-edged diamonds are used by eye surgeon in catract surgery.
• Being extra ordinarly sensitive for heat radiations and having property to remove immediately harmful radiations. These are used in making absolute thermometers.

Question 6.
Why do diamonds glitter?
Answer:
Diamond is a transparent substance whose refractive index is very high. The rays of light passing through it get diverted much. According to its cut base edges light rays undergo total internal reflection. When these edges are polished, diamond glitters very beautifully.

Question 7.
How are diamonds made naturally and artifically?
Answer:
Naturally, diamonds are made by carbon present at the depth of about 150 km, where pressure is 70,000 atm and the temperature is about 1500°C. These diamonds come up near the surface with special kimberlite rocks. Artifically, diamonds are made by heating graphite under high pressure in the presence of special catalysts.

Question 8.
Write the structure of graphite. Why is it so soft?
Answer:
Each carbon atom is bonded with three neighbouring carbon atoms with covalent bonds in graphite. They are always in the same plane giving hexagonal array. As compared to diamond, the distance between carbon atoms is more. The distance between upper and lower layers does not permit carbon atoms to make covalent bonds and because of this fourth electrons remains free. These layers can easily slide one upon the other and graphite attains the property of a lubricant. It is very soft and slippery.

Question 9.
Why are diamonds used in jewellery? Give reasons.
Answer:
Refractive index of diamond is 2.45 which is the highest of all known substances, because of this, it shines brightly. Its critical angle is 24°, which is very less. This is why, the light rays passing through it deviates much. A small deviation in it causes beautiful spectrum of colours. When the bases of diamond are polished, it produces an astonishing brightness. That is why diamonds are used in making jewellery.

Question 10.
Why is graphite a good conductor of electricity?
Answer:
Each carbon atom of graphite is surrounded by three carbon atoms joined with covalent bond which makes hexagonal layers over each other. In these layers distance between the carbon atoms is more, that is why the possibility of fourth covalent bond between the carbon atoms of opposite layers is reduced. The fourth covalent electron is set free. The graphite has easy flow of electrons and it acts as a good conductor of electricity.

Question 11.
What are the uses of graphite?
Answer:
Uses of Graphite

• It is good conductor of electricity so- it is used in making dry cells and electric arcs as electrods.
• It is used in making pencils, black colour and black paint.
• It has lubricant property so it is used in machines to keep them lubricating at high temperature.
• It is used in making crucibles to boil some metals because of its high melting point.

Question 12.
Why are allotropes of carbon in form a molecule known as fullerenes?
Answer:
The allotropes of carbon in which 60 carbon atoms join to form a molecule are termed as fullerene. US architect Buckminster Fuller designed three dimensional domes which were supported by pentagonal and hexagonal structures.

Since fullerene molecules looked like these domes, that is why they are known as fullerene.

Question 13.
Draw the electron dot structures of methane, ethane, ethene, butane.
Or
(i) Write molecular formula of butane.
(ii) Draw the structure of Propanal.
Answer:
Methane
Formula -CH₄

Ethane
Formula -C₂H₆

Ethene
Formula -C₂H₄

Or
(i) Butane
Formula – C₄H₁₀

(ii) Propanal

Question 14.
Write two tests of alcohol.
Answer:

1. Ester test: When alcohol is heated with acetic acid, in the presence of sulphuric acid, sweet smelling ester is produced.
2. Sodium test: Alcohol reacts with sodium metal and always produces hydrogen gas.

Question 15.
(a) What do you understand by homologous series? Explain with an example.
Answer:
Homologous series. A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series. Each successive member differ by (- CH₂) group. All the members of a homologous series can be obtained by similar process.

General Formula : C_nH_2n+2
For example : Homologous series of alkane is as follows

(b) Write the first three homologous compounds of methane.
Answer:
Homologous Compounds of Methane

Question 16.
Define homologous series. What are its main properties?
Answer:
Homologous series. A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called homologous series. In this series the adjacent members differ by (-CH₂) group. Each member of a homologous series is called homolog.

Properties of Homologous Series :

• All the members of a homologous series can be represented by a common formula.
• Two successive members differ by one carbon atom and 2 hydrogen atoms.
• All the members of a homologous series possess similar chemical properties.
• There is a small difference between all the members of a homologous series.
• There is always a difference of 14 a.m.u. in atomic mass of two adjacent homologous.

Question 17.
What are alkanes? Write the properties of its main members. What do we conclude from its properties?
Answer:
Alkanes. The hydrocarbons with structural/general formula C_nH_2n+2 are called alkanes. The members of this group form an homologous series. Hydrocarbons like methane, ethane, propane and butane form many carbonic compounds which are collectively known as alkane. In these compounds, the number of carbon and hydrogen atoms differ by (- CH₂) for the next member of family.

Properties of Alkanes

Conclusions:

• Physical properties of alkane are based on their mass.
• First four members of alkane are in gasous state and alkanes having more than six carbon atoms are in liquid state.
• Alkanes having high molecular mass are found in solid state.
• Melting and boiling point of alkanes increase with increase in molecular mass.

Question 18.
What happens when hydrogen gas is passed through vegetable oils in the presence of nickel?
Answer:
Vegetables oils have double bond and polymerisation is possible. When nickel is used as catalyst, vegetable oil converts to vegetable ghee when hydrogen is passed through it because of hydrogenation. Vegetable ghee is solid like butter at room temperature.

Question 19.
Write the chemical properties of ethanoic acid.
Answer:
Ethanoic acid reacts with some metals, metal carbonates, hydroxides and bicarbonates.
1. Action with sodium:

2. Action with sodium hydroxide and potassium hydroxide:

3. Action with carbonate and hydrogen carbonate :
It reacts with carbonates and hydrogen carbonate to form water, salt and carbon dioxide.

Question 20.
Which type of oils should be used for cooking? Why?
Answer:
Animal fats have saturated fatty acids, which are harmful for health, whereas oils have long unsaturated carbon chains which are not harmful. Hence unsaturated fatty acids oils are used for cooking.

Question 21.
Write the ill-effects of using alcohol.
Answer:

• It is an addictive substance.
• It affects the sensitivity of nervous system.
• When a drunken person drives the vehicle he/she is not able to take the right decisions which leads to accident.

Question 22.
Why is consumption of methanol (CH₃OH) very fatal?
Answer:
Even a very small amount of methanol can prove fatal. In liver, it oxides to form methanale, which vigorously react with cells of liver, by which protoplasm gets emanating and swells in the same manner as boiled egg. Consumption of methanol also lead to blindness.

Question 23.
Write the IUPAC names of ethyl alcohol and acetic acid. Write the name of products formed when ethyl alcohol and acetic acid react in the presence of concentrated sulphuric acid. Write its chemical reaction.
Answer:

Compounds	IUPAC Names
1. Ethyl alcohol	ethanol
2. Acetic acid	ethanoic acid

Chemical reaction :

Question 24.
How will you prepare :
(a) ethyl alcohol from ethene
(b) acetic acid from ethyl alcohol?
Give reactions.
Answer:
(a) Ethene is heated with water in the presence of phosphoric acid to prepare ethyl alcohol

(b) Acetic acid is prepared by oxidation of ethyl alcohol

Question 25.
Write in brief the various industrial alcohols.
Answer:

• Absolute alcohol: It is 100% pure ethanol. It is produced by fractional distillation of ethanol which is prepared by fermentation of carbohydrates.
• Denatured alcohol: It is 95% ethanol and is used in industries. It is made poisonous by adding methanol, copper sulphate and pyridine, so as to make it unfit for drinking.
• Power alcohol: It is mixture of Benzene and Ether in 20% Ethanol and 50% gasolene. It is used to save petroleum.
• Alcoholic beverages: Alcohol is used as addictive drink. It is sold under various names like, rum, whisky, brandy, Jinn, etc.

Question 26.
Why is cleansing effect of soap not effective in hard water?
Answer:
Soaps are not effective in hard water for washing purposes because hard water has salts of calaium and magnesium. When soaps are dissolved in hard water, calcium and magnesium ions l’eact with water to form calcium and magnesium salts of fatty acids.

That is why a large amount of soap gets wasted. Calcium and magnesium salts being insoluble in water make precipitates and they get attached with the clothes and cause hinderance to the cleaning action and the clothes are not cleaned properly.

Question 27.
Distinguish between soaps and detergents.
Answer:

Soaps	Synthetic detergents
1. Soaps are sodium or potassium salts of higher fatty acids e.g. Sodium Stearate.	1. Synthetic detergents are Sodium alkyl Sulphates or Sodium alkyl benzene sulphates.
2. Soaps are prepared from vegetable oils or animal fats.	2. Synthetic detergents are prepared from the hydrocarbons obtained from petroleum.
3. Soaps have relatively weak cleansing action.	3. They have strong cleansing action.
4. Soaps form curdy white precipitates with calcium and magnesium salts present in hard water and hence, are not used in hard water.	4. Calcium and magnesium salts of detergents are soluble in water. Therefore no curdy white precipitates are obtained in hard water and hence synthetic detergents can be used even in hard water.
5. Soaps cannot be used in acidic medium as they are decomposed into carboxylic acids in acidic medium.	5. They can be used in acidic medium as they are the salts of strong acid and are not decomposed in acidic medium.
6. Soaps do not cause water pollution.	6. Synthetic detergents cause water pollution.
7. Soaps are biodegradable.	7. Some of the synthetic detergents are non biodegradable.

Question 28.
Write the formation of ethanol by fermentation process.
Answer:
Fermentation occurs in the presence of Bio-chemical catalysts at normal temperature by which sugar molecules convert into alcohol and carbon dioxide. These catalysts are known as enzymes, which means ‘yeast’ or ‘in the fermentation’.

Alcohol is formed by fermentation of sugar or starch. In a beaker, grape juice or glucose mixture is heated at 20° – 30°C in the presence of yeast. Sugar or starch molecules break into smaller molecules which produce carbon dioxide due to process of fermentation. This carbon dioxide is expelled out but air is not given inlet. A dilute mixture of ethanol is formed in water during fermentation. Ethanol is purified by distillation.

Chemical reaction :

Question 29.
Write the name of the reaction in which ethanoic acid and ethanol react together to form one product. Write the common name of the product.
Answer:
When ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid, ester is produced and this process is known as esterification.
CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Question 30.
Observe the figure given below :

(i) Write the reaction taking place
Answer:

(ii) What is this reaction called?
Answer:
Esterification

Question 31.
What is indicated in the figure given below and give use of it.
Answer:
The figure indicates formation of micelle. Micelles are used to remove oily dirt from clothes.
1 – Hydrophilic end
2 – Oil droplet.

Question 32.
Show the bonds of Hydrogen, Oxygen and Nitrogen atoms respectively.
Answer:
1. Hydrogen: Two atoms of hydrogen by sharing of their electrons make hydrogen molecule (H2).

2. Oxygen: A double bond is made between two atoms of oxygen. Each atom of oxygen shares two electrons with other atom to form .an octet.

3. Nitrogen: Each atom of nitrogen shares three electrons to form an octet.

Question 33.
(i) Write molecular formula of Propane.
Answer:
C3H8

(ii) Write IUPAC name of

Answer:
Bromoethane.

Question 34.
What is detergent? Write the formation of synthetic detergents. Write its advantage.
Answer:
Materials used for cleaning purposes are known as detergents. Since long, soaps have been used as detergents but now-a-days synthetic detergents are more popular. The detergent molecule has two ends, one which is made of sulphate (-SO₄) or sulphonate (SO₃Na) group and it is hydrophilic by nature whereas other which is made of hydrocarbon is hydrophobic.

Synthetic detergent produces ample amount of lather even in hard water. These do not form insoluble salts of calcium or magnesium.

Question 35.
Which substances are used to produce synthetic detergents?
Answer:
Following substances are needed for production of synthetic detergents :

• Long chained hydrocarbons obtained from petroleum and coal.
• Concentrated sulphuric acid.
• Sodium hydroxide.

Procedure: Hydrocarbons are treated with cone, sulphuric acid to get hydrocarbonic sulphuric acid. It is further reacted with NaOH which forms synthetic detergents. About 15 to 30% of the total weight of washing powder is detergent. Rest of the others are various chemicals which provide other qualities.

Question 36.
What are the components of washing powder?
Answer:

• Synthetic detergents (15 to 30%).
• Sodium sulphate and sodium nitrate.
• Sodium tri-poly phosphate or sodium carbonate.
• Sodium perborate.

Very Short Answer Type Questions

Question 1.
Which element is present necessarily in the following items?
Food, clothes, medicines and hooks.
Answer:
Carbon.

Question 2.
On which element do all living processes depend?
Answer:
Carbon.

Question 3.
What percentage of carbon is present in minerals found under the crust of earth?
Answer:
0.02 %.

Question 4.
What percentage of CO₂ is present in atmosphere?
Answer:
0.003%.

Question 5.
How many electrons are present in the outer shell of carbon?
Answer:
4.

Question 6.
Why does carbon need four electrons to gain or lose?
Answer:
To attain noble gas configuration.

Question 7.
How does carbon gain four electrons?
Answer:
By making C₄^– anion.

Question 8.
How does carbon lose four electrons?
Answer:
By making C₄⁺ cation.

Question 9.
Which type of bond is shared by a pair of two hydrogen atoms?
Answer:
Single bond.

Question 10.
How is single bond between two atoms expressed?
Answer:
By single straight line.

Question 11.
What is the atomic number of nitrogen?
Answer:
7.

Question 12.
How many electrons are given by each atom of Nitrogen to complete the octet?
Answer:
3.

Question 13.
Which gas is used as a fuel the most?
Answer:
Methane gas.

Question 14.
Methane is the main constituent gas of which two fuel gases?
Answer:
Biogas, C.N.G.

Question 15.
Write the full form of C.N.G.
Answer:
Compressed Natural Gas.

Question 16.
How is the structure of diamond?
Answer:
Strong three-dimensional structure.

Question 17.
How is the structure of graphite?
Answer:
Hexagonal.

Question 18.
Which of these two is a good conductor of electricity diamond or graphite?
Answer:
Graphite.

Question 19.
Which is the hardest substance?
Answer:
Diamond.

Question 20.
How does it feel by touching graphite?
Answer:
Soft and slippery.

Question 21.
Which element has the ability to form large number of compounds?
Answer:
Carbon.

Question 22.
Give names of two elements which are placed in the group of carbon and have same valency.
Answer:
Valency of carbon is 4. This group has silicon and germanium.

Question 23.
What is the simplest form of hydrocarbon?
Answer:
Methane (CH₄).

Question 24.
In which types of bonds can carbon atoms join?
Answer:
Single, double, triple bond and ring-shaped.

Question 25.
Write the names of five elements which can make bond with carbon to form new compounds.
Answer:
Oxygen, Hydrogen, Nitrogen, Sulphur, Chlorine.

Question 26.
Write the formula of Ethane.
Answer:
C₂H₆.

Question 27.
Write the structural formula of Ethane.
Answer:

Question 28.
Give the next higher homo-logues of:
(i) C₃H₆
Answer:
C₄H₈

(ii) C₆H₈.
Answer:
C₇H₁₀.

Question 29.
Give the structure of ethanol.
Answer:

Question 30.
Name the functional group in propanone.
Answer:

Question 31.
Give the structure of simplest ketone.
Answer:
Simplest keton is acetone. It has the structure :

Question 32.
Give the name and structure of four carbon atoms in aldehyde.
Answer:

Question 33.
Name the products obtained when ethanol undergoes complete combustion.
Answer:
Carbon dioxide (CO₂) and Water (H₂O).

Question 34.
Give the structural formula of ethanol.
Answer:

Question 35.
Give the name and structure of functional group present in acetic acid (CH3COOH).
Answer:
Carboxyl group

Question 36.
Which of the following compounds belong to same homo-Iogous series?
C₂H₆O₂, C₂H₆O₂, C₂H₆, CH₄O
Answer:
C₂H₆ O, (C₂H₅OH) And CH₄O or (CH₂OH).

Question 37.
Give the structural formula of an ester.
Answer:

Question 38.
Give the names and structural formulas of acid and alcohol from which ethyl acetate is obtained.
Answer:
Acetic acid

and ethyl alcohol, CH₃CH₂OH

Question 39.
Give the electron-dot stucture of methane.
Answer:

Question 40.
Define covalent bond.
Answer:
It is formed by mutual sharing of electron pair between two atoms.

Question 41.
Explain what covalent compounds do not conduct electric current?
Answer:
This is because there are neither free ions nor free electrons.

Question 42.
Name the bond formed between metal atom and non-metal atoms.
Answer:
Ionic or electro valent bond.

Question 43.
What are allotropes?
Answer:
When an element exists in two or more form having different physical pruperties but, some chemical properties, there forms are called allotropes.

Question 44.
Define catenation.
Answer:
It is the property due to which a large number of atoms of the same element get linked together through covalent bonds forming long straight chains, branched chains and rings of different sizes.

Question 45.
Give two oxidising agents.
Answer:

1. Acidified potassium permanganate.
2. Acidified potassium dichromate.

Question 46.
Give the electron dot structure of ethane.
Answer:
Dot structure of ethane :

Question 47.
Give the structural formula of propane.
Answer:

Question 48.
Give the electron dot structure of ethene.
Answer:
Dot structure of ethene.

Question 49.
Define functional group.
Answer:
It is an atom or group of atoms which when present in a molecule gives special properties to it. e.g. C₂H₅OH has the functional group, -OH (hydroxyl group).

Question 50.
If two organic compounds have some functional group, predict they have similar physical or chemical properties.
Answer:
Similar chemical properties.

Question 51.
Give the general formulae of alkanes, alkenes and alkynes.
Answer:
Alkanes: C_n H_2n+2
Alkaenes: C_nH_2n
Alkynes: C_nH_2n-2, where n = No. if carbon atoms).

Question 52.
Give the structural formula of isomers of C₄H₁₀ (butane).
Answer:
Butane has two structural isomers :

Question 53.
Give the first four members of homologous series of alcohols.
Answer:
CH₃OH, C₂H₅OH. C₃H₇OH, C₄H₅OH.

Question 54.
Define a Catalyst.
Answer:
It is a substance which can increase the rate of a reaction but remains unchanged in mass and composition at the end of reaction.

Question 55.
What happens when a piece of sodium metal is added to ethanol? Give chemical equation also.
Answer:

Question 56.
What happens when ethanol is heated with conc. H₂SO₄ at 443K?
Answer:
Ethanol undergoes acidic dehydration to give ethene

Question 57.
What is denatured spirit or alcohol?
Answer:
It is prepared by adding poisonous substance like methanol, acetone, pyridine or copper sulphate to ethanol. It is unfit for drinking purposes.

Question 58.
Give three uses of ethanoic acid.
Answer:

1. In the manufacture of vineger
2. In the manufacture white lead
3. As a reagent in laboratory.

Question 59.
What is the atomic number of hydrogen?
Answer:
One.

Question 60.
Give the electronic configuration of carbon atom.
Answer:
(2, 4).

Question 61.
Give name of four carbon compounds.
Answer:
Methane, Chloroform, Ethanol and ethanoic acid.

Question 62.
Give two allotropic forms of carbon.
Answer:
Diamond and graphite.

Question 63.
Give the name of simplest ketone.
Answer:
Propanone (CH₃ COCH₃).

Question 64.
Give the name of first member of homologous series of alkynes.
Answer:
Ethyne (C₂H₂).

Question 65.
Give the name and formula of acid present in vinegar.
Answer:
Ethanoic acid (CH₃ COOH).

Multiple Choice Questions:

Question 1.
Ethanoic acid has the formula:
(A) C₂H₅OH
(B) CH₃COCH₃
(C) CH₃COOH
(D) C₂H₅COOH.
Answer:
(C) CH₃COOH

Question 2.
Carboxylic acids contain functional group:
(A) -CHO
(B) -CH₂OH
(C) -COOH
(D) -OH.
Answer:
(C) -COOH

Question 3.
The general formula of the alkyne is:
(A) C_nH_2n-2
(B) C_nH_2n+2
(C) C_nH_2n
(D) C_nH_2n+2.
Answer:
(A) C_nH_2n-2

Question 4.
Propanone has the functional group :
(A) -OH
(B) -CHO
(C) C=O
(D) -COOH.
Answer:
(C) C=O

Question 5.
Vinegar contains acetic acid:
(A) 5-8%
(B) 15-20%
(C) 21-29%
(D) 30-40%.
Answer:
(A) 5-8%

Question 6.
The reaction of acetic acid with ethyl alcohol is called :
(A) Polymerisation
(B) Saponification
(C) Hydrogenation
(D) Esterification.
Answer:
(D) Esterification.

Fill in the Blanks :

Question 1.
The functional group present in ethyl alcohol is ___________
Answer:
The functional group present in ethyl alcohol is alcoholic group (-OH)

Question 2.
CH₃—CH₂—OH represents ___________
Answer:
Ethyl alcohol.

Question 3.
Two atoms of the same element combine to form a molecule. The bond between them is known as ___________ bond.
Answer:
Covalent.

Question 4.
In the formation of oxygen molecule, the oxygen atoms share ___________ electrons each.
Answer:
Two.

Question 5.
The number of single covalent bonds in the molecule of ammonia is ___________
Answer:
Three.

Punjab State Board PSEB 9th Class Science Important Questions Chapter 5 The Fundamental Unit of Life Important Questions and Answers.

PSEB Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

PSEB 9th Class Science Guide The Fundamental Unit of Life Textbook Questions and Answers

Question 1.
Make a comparison to write down ways in which plant cells are different from animal cell.
Answer:

Features	Plant Cell	Animal Cell
1. Cell wall	Cell wall is formed of cellulose.	Cell wall is absent.
2. Centrosome	Absent.	Present.
3. Vacuoles	Large-sized and many present, small-sized.	Generally absent but if only a few.
4. Plastids	Present.	Absent.
5. Reserve food	In the form of starch and paramylon.	In the form of glycogen
6. Nucleus	Central.	Acentric away from centre.

Question 2.
How is prokaryotic cell different from a eukaryotic cell?
Answer:
Differences between prokaryotic cell and eukaryotic cell

Prokaryotic cell

Eukaryotic cell

1. Found in Bacteria, blue-green algae and , Mycoplasma. 2. Primitive nucleus called nucleoid present. Chromosome is single, circular and double-stranded DNA but no proteins (so naked), No nuclear membrane. 3. Cell wall when present, it is formed of peptidoglycan. 4. Membrane-bound Cell-organelles like mitochondria, plastids, E.R., golgi bodies etc. is absent. 5. Ribosomes are of 70 S type. 6. Small-sized (1 – 10 um). 7. Cell division by fission or budding.

Found in Protista, Fungi, Plantae and Animalia. 2. A true nucleus present. Chromosomes are two to man, linear and formed of DNA and histones. Nuclear membrane present. 3. Cell wall when present in plant cells it is formed of cellulose. 4. Membrane-bound Cell-organelles like mitochondria, plastids, E.R., golgi bodies etc. is present. 5. Ribosomes are of 80 S type. 6. Large-sized (5 – 100 /un). 7. Cell division bv mitosis and meiosis.

Question 3.
What would happen if a plasma membrane ruptures or breaks down?
Answer:
Plasma membrane maintains the shape and protects the organelles. If it gets ruptured the internal organisation will be lost and it will not be able to perform its function. Then cell wall die and contents of cell will get disintegrated.

Question 4.
What would happen to the life of a cell if there was no Golgi apparatus?
Answer:
1. The Golgi apparatus performs the function of storage, modification and packaging of materials synthesised in the cell. These materials will not be able to perform their function in its original form.
2. The formation of lysosomes will be affected.

Question 5.
Which organelle is known as the powerhouse of the cell? Why?
Answer:
Mitochondria are known as ‘power house’ of the cell. They are sites for synthesis, storage and transport of ATP (Adenosine triphosphate) commonly called energy currency.

Question 6.
Where do the lipids and proteins constituting the cell membrane get synthesised?
Answer:

• Proteins are synthesised bv ribosomes.
• SER is site for synthesis of lipid.
• These proteins and lipids are modified by golgi apparatus to form plasma membrane.

Question 7.
How does an Amoeba obtain its food?
Answer:
Plasma membrane is flexible and it enables the cell to engulf in food and other materials from the external environment. Such a process is termed endocytosis.

Question 8.
What is osmosis?
Answer:
Osmosis. It is a special case of diffusion of water through a selectively permeable membrane. It is a passage of water from a region of higher concentration through a semi- permeable membrane to a region of low water concentration.

Question 9.
Carry out the following osmosis experiment:
Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) keep cup A empty
(b) put one teaspoon sugar in cup B
(c) put one teaspoon salt in cup C
(d) put one teaspoon sugar in the boiled potato cup D.
Keep this setup for two hours. Then observe the four potato cups and answer the following.
1. Explain why water gathers in the hollowed portion of B and C.
2. Why is potato A necessary for this experiment?
3. Explain why water does not gather in the hollowed out portions of A and D?
Answer:
1. The water gathers in hollowed portion of potato cups B and C due to osmosis.
2. Cup A acts as control experiment and indicates that cavity of potato will not induce any type of movement.
3. Cup A does not contain hypertonic solution hence water does not rise. In cup D, cells of potato cup being boiled cells are dead and no osmosis occurs.

Science Guide for Class 9 PSEB The Fundamental Unit of Life InText Questions and Answers

Question 1.
Who discovered cell and how?
Answer:
Robert Hooke (1665) discovered cell for the first time. He examined a thin slice of cork under the microscope. He observed that cork resembled the structure of a honey comb consisting of many hexagonal compartments and called these boxes ‘cells’.

Question 2.
Why is cell called the structural and functional unit of life?
Answer:

1. Cells are arranged in proper and systematic order to form a body of living organism. Thus cells serve as basic building structural units for more complex organisms.
2. Cell is also functional unit of life because all the metabolic activities of life take place at cell level.
3. Respiration, digestion, excretion and reproduction occur at cell level.
4. Cells contain genetic material which regulate cell functions and pass on all information to the next generation.

Question 3.
How do substances like C0₂ and water move in and out of the cell? Discuss.
Answer:
The substances like C0₂ and water move in and out of cell by the process of diffusion. There is spontaneous movement of substances from higher concentration to lower concentration. The movement of water across selectively permeable membrane is called osmosis.

Question 4.
Why is the plasma membrane called selectively permeable membrane?
Answer
Plasma membrane permits the entry and exit of selected materials in and out of the cell. It also prevents movement of some materials required within the cell. The membrane is called selectively permeable membrane.

Question 5.
Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.

Prokaryotic Cell	Eukaryotic Cell
1. Size: generally small (1 – 10 µm) = 10-6m 2. Nuclear region ……………. and known as ……………….. 3. Chromosome single. 4. Membrane-bound cell organelles absent.	1. Size: generally large 5 – 100 µm 2. Nuclear region well defined and surrounded by a nuclear membrane. 3. More than one. 4. ………………………………………………..

Answer:
2. Nuclear region undefined due to absence of nuclear membrane and known as Nucleoid.
4. Membrane-bound cell organelles such as mitochondria, Golgi bodies, chloroplast, etc. are present.

Question 6.
Can you name two organelles we have studied that contain their own genetic material?
Answer:

• Chloroplasts
• Mitochondria.

Question 7.
If the organization of the cell is destroyed due to some physical or chemical influence, what will happen?
Answer:
Each cell has certain special cell organelles. Each performs a special function. If an organization is destroyed cell will stop performing basic functions and result in its death.

Question 8.
Why are lysosomes called ‘suicidal bags’?
Answer:
Lysosomes are membrane-bound sacs filled with enzymes and this enzyme may digest their own contents if burst. They carry out autolysis (auto = self; lysis = break down) hence called “suicidal bags.”

Question 9.
Where are proteins synthesized inside the cell?
Answer:
Proteins are synthesized on the ribosomes which are attached to the surface of RER or lie freely in the cytoplasm. Ribosomes are also called “protein factories” of cells.

Punjab State Board PSEB 10th Class Science Important Questions Chapter 3 Metals and Non-metals Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 3 Metals and Non-metals

Long Answer Typt Questions

Question 1.
Show various steps involved in extraction of metal from an ore by a sketch.
Answer:

Steps involved in the extraction of metals from ores.

Question 2.
Give methods of enrichment of ores.
Answer:
Methods of enrichment of ores. Ores or minerals are mined from earth these are usually contaminated with large amount of impurities which are called gangue. It is necessary to remove these impurities before extraction of metals. By removing gangue the ore is enriched and concentration of metal is increased. Therefore ore in enriched prior to other processes. Methods of removing gangue from ore depends on the difference of physical and chemical properties of both of them.

Enrichment of ore using magnetic method.

Physical methods of enrichment :

• Hydraulic Washing: In this method finely powdered ore is washed with jet of water. In this strong flow of water light gangue particles are washed away where as heavy ore particles settle down, Tin and lead ores are enriched by this method.
• Froth Floatation Method: In this method, mixture of powdered ore and water or some appropriate oil is taken in a tank. Ore particles are coated with oil and gangue particles are wet with water. A blast of compressed air is blown through the pipe of a rotating agitation to produce froth, due to this, mineral particles wetted with oil change into foam and float on the surface of water. Froth containing ore particles is easily transferred to another container sulphides of copper, lead and zinc are enriched by this method.

Chemical Methods: The chemical method used for the concentration of the ore is based on the difference in some chemical property of the metal and the impurities. An example of this method is the concentration of bauxite ore of aluminium.

Concentration of aluminium ore by Bayer’s process: In this method, Bauxite is reduced by treating it with hot sodium hydroxide. It gives sodium meta aluminate (NaAlO₂) which is soluble in water. The solution in filtered to remove the gangue present in the ore because it does not dissolve in sodium hydroxide. NaAlO₂ is allowed to react with hydrochloric acid to obtain Aluminium hydroxide. On strong heating aluminium hydroxide pure aluminium oxide is obtained.

Following reactions take place

Question 3.
Explain General methods used in the extraction of metals.
Answer:
Steps involved in the extraction of metals :

• Enrichment (concentration) of ore.
• Converting concentrated ore into oxide.
• Reduction of metal oxide to obtain metal.
• Refining of impure metal.

1. Concentration :
(A) Hydraulic washing: This method is used for concentration of oxide ores Gangue particles are lighter as compared to ore particles. In this method powdered ore is washed with flowing water. Light gangue particles are washed away with water and heavy ore particles are left.

(B) Froth floatation method: In this method powdered ore is taken in a tank containing water pine oil is also added to it. Sulphide ore is wet with oil and gangue is wet with water.

The water is agitated by blowing compressed air violently, a froth is formed on the surface of water. This froth carries the lighter ore particles along with it to the surface. Gangue particles are heavy and settle to the bottom.

(C) Magnetic separation.

Enrichment of ore using magnetic method.

1. Magnetic method: This method is acceptable for magnetic impurities like iron, cobalt, Nickel etc. Minerals which are of magnetic nature got attracted towards magnetic field. Chromite and pyrolusite ores are enriched by this method. In this method ground ore is placed on a conveyer belt. This belt goes around two rollers one of which is magnetic. When ore comes near the magnetic roller then two heaps of magnetic and non magnetic materials are obtained. Iron ore magnetite is enriched by this method.

(D) Chemical separation: This process is based on the difference between chemical – properties of ores and gangue eg. Bauxite Al₂O₃.2H₂O is impure form of aluminium oxide. It contains Iron (III) oxide (Fe₂O₃) and sand (SiO₂) as main impurities. Due to iron (III) oxide its colour is red brown. Bayer’s process is used to obtain pure aluminium from / bauxite. In this methods powdered ore is mixed with heated sodium hydroxide.
Al₂O₃ (S) + 2NaOH (aq) → 2NaAlO₂ (aq) + H₂O (l)
NaAlO₂ (aq) + 2H₂O (l) → Al(OH)₂ (s) + NaOH (aq)

2. Converting concentrated ore into metal oxide
Roasting: In this process ore is heated in the presence of air to obtain metal oxide. Which can easily be reduced to obtain the metal.

Zinc blende contains zinc sulphide when concentrated zinc blende ore (zinc sulphide) is roasted in air then it gets oxidized to give zinc oxide.

Calcination: In this process ore is heated in the absence of air to remove moisture and volatile impurities.
When carbonate ore is heated it dissociates to give metal oxide.

3. Extracting metals from metal oxide.
To obtain metal from metal oxide it is heated with some reducing agent. To obtain metals zinc, iron, tin etc. their oxides ore heated with carbon which acts as reducing agent.
ZnO(s) + C(s) → Zn(s) + CO(g)

Oxides of metals with medium activity can be reduced by using highly reactive metals like sodium, calcium and aluminium etc.
3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(s) + heat

4. Electrolytic refining.
In this method impure metal is taken as anode and a thin strip of pure metal is taken in the form of cathode metal salt solution is taken as electrolyte. When electric current is passed through the electrolyte, pure metal from anode dissolves into solution and impurities settle down as anode mud.

Electrolytic refining

Question 4.
(a). How do metals and non-metals react?
Answer:
Metals and non-metals react on the basis of electronic configuration in the valence shell.

Sodium has only one electron in its outer most shell. If it lose its electrons of the M shell then L will become its outermost shell which have complete octet. Nucleus of this atom will have 11 protons but number of electrons is 10, therefore it is positively charged and gives Na+ sodium positive ions. On the other side, there are 7 electrons in the outer most shell of chlorine and it requires one electron to complete its octet. If there is reaction between chlorine and sodium then lost electron of sodium atom is gained by chlorine atom and chlorine atom becomes negatively charged by one unit. Because there are 17 protons in the nucleus of the chlorine atom and there are 18 electrons in K, L and M shells. Therefore, chloride negative ions Cl- is obtained.

Due to opposite charges sodium and chloride ions attract each other and they form strong bonds involving electrostatic forces and form sodium chloride.

Another ionic compound, magnesium chloride is shown in fig.
Formation of NaCl and MgCl₂ by Electron transfer :

Formation of sodium chloride.

Formation of sodium chloride.

Compounds formed by metals and Non-Metals by the transfer of electrons between them are called ionic or electrovalent compounds.

(b) Write four main exceptions from normal properties of metals and Non-Metals.
Answer:

• All the metals are solid at room temperature except mercury. Melting point of metal is usually high but of Gallium and Cesium is low.
• Iodine is a non-metal but still shiny.
• Carbon is a non-metal which can have many forms. Diamond is allotrope of carbon. It is the hardest substance found in nature. Its melting and boiling point are very high. Another allotrope of carbon is graphite which is conductor of electricity.
• Alkali metal (lithium, sodium, Potassium) are so soft that these can be cut by knife. They have low density and low melting point.

Question 5.
How will you differentiate between metals and non-metals?
Answer:
Differences between metals and non-metals on the basis of physical properties :

Metals	Non-metals
1.         All metals are solid at room temperature. But mercury is liquid at room temperature.	1. Non-metals exist in all the three states at room temperature. Phosphorous and sulphur are solid, H2, O2, N2 in gaseous state, and bromine in liquid state.
2. Metals are ductile, malleable and tenacious.	2. These are soft.
3. Metals have lustre i.e. metal shine.	3. They do not have lustre but diamond, graphite and iodine are exceptions.
4. Metals are good conductors of heat and electricity but bismuth is exception.	4.All non metals are non conductors except graphite and carbon gas.
5. Metals have high melting and boiling points.	5. Non metals have low melting and boiling points.
6. Metals are hard but sodium and potassium can be cut by knife.	6. These are not very hard but diamond is the hardest substance.
7. Metals have very high relative densities but Na, K are exceptions.	7. Non metals have very low relative densities.
8. Metals are opaque.	8. Gaseous non metals are transparent.

Difference between metals and non-metals on the basis of chemical properties

Metals	Non-metals
1. Metals form alkaline oxides some of them form bases.	1. Non-metals form acidic or neutral oxides.
2. Metals react with acids to displace hydrogen and form salts.	2. Non-metals do not displaces hydrogen from acids.
3. Metals are electropositive in nature.	3. Non-metals are electronegative in nature.
4. Metals combine with chlorine to form chlorides which are electrovalent compounds.	4. Non-metals combine with chlorine to form chlorides which are covalent compounds.
5. Some metals combine with hydrogen to form hydrides which are electrovalent.	5. Non-metals combine with hydrogen to form hydrides which are covalent.
6. Metals are reducing agents.	6. Non-metals are oxidizing agents.
7. Metals form positive ions in aqueous solution.	7. Non-metals form negative ions in aqueous solution.

Question 6.
Discuss about the extraction of metals
Answer:
Some metals are found in free state in nature. Some metals are found in the form of compounds. Metals at the bottom of reactivity series show very low reactivity. These are found in free state. Gold, silver, platinum and copper are found in free state.

Copper and silver are also found in the form of sulphide and oxide ores. Metals (K, Na, Ca, Mg and Al) which are at the top of reactivity series show very high reactivity that they are never found in free state. Metals at the middle of the reactivity series (Zn, Fe, Pb etc.) are moderately reactive. These are found in the form of oxide, sulphide or carbonate. Some metal ores are found in the form of oxides.

Metals are classified into three types:
(a) least reactive metals
(b) Moderately reactive metals
(c) highly reactive metals.

Reactivity series and metallurgy

Question 7.
What is rust? What are the requirements necessary for its completion? Give ways to prevent rusting of iron?
Answer:
Surface of iron aquires a coating of a brown flaky substance called rust. It is a compound of Iron (III) Oxide and iron (III) hydroxide. It weakens the iron surface. Due to this, a great loss occurs to the iron articles.

The presence of moisture and air is necessary for rusting of iron. This can be proved with an experiment. If we take new shining irons nails in three test tubes as shown, then we find that nails which are in contact with water and air, got rusted. If we completely immerse the nails in water and cover the water surface with oil so that there is no air available for the nails, then nails will not get rusted.

Similarly if we use CaCl, in the test tube absorbs all the moisture so that no moisture is available in this case also, nails will not get rusted.

Ways to Prevent Rusting :

1. Using oil or grease on the surface: If iron surface is covered with oil or grease it does not remain in contact with air and thus rusting is prevented. Machine parts are saved by this method.
2. Using enamel: By painting iron surface, rusting can be prevented. Buses, cars, scooter, motor cycle, windows, trains etc. are saved by this method.
3. Covering with plastic: Iron surface is covered with plastic. Iron furniture is saved by this method.
4. Galvanization: A process of coating thin layer of zinc on iron is called galvanization. This method is used to prevent buckets, tubs, drums, iron sheets etc. from rusting.
5. By electroplating: Iron can be electroplated by metals like Nickle, Chromium, aluminium etc. Rims, handles, bumpers etc. of vehicles are prevented from rusting by this method.
6. By tin: Iron is coated with tin. Ghee canisters, boxes used for packing food are tinned.
7. Converting to steel: Iron can be preverted from rusting by converting it into steel.

Question 8.
Explain General properties of ionic compounds.
Answer:
General properties of ionic compounds are given below:

• Physical nature: Due to strong force of attraction between positive ions and negative ions, ionic compounds are solid. They are brittle and break on pressing.
• Melting and boiling point: They have high melting and boiling points. Because a large amount of energy is required to break the strong inter ionic attraction.
• Solubility: Ionic compounds are normally soluble in water but are insoluble in Kerosene, Petrol etc.
• Electric Conductivity: In solid form ionic compounds do not conduct electricity because of strong and firm structure. Movement of ions is not possible. But ionic compounds can conduct electricity in molten state, because electrostatic force of attraction becomes very weak due to heat energy. Therefore ions can move freely and electric current can pass through it. Mobility of charged particles is necessary for conduction of electricity in a solution. Ions are present in aqueous solution of ionic compounds. When electric current is passed through the solution then ions start moving towards the opposite electrodes.

Question 9.
What is an alloy? Magnetic iron oxide explain the objective of their formation?
Answer:
Alloy: An alloy is a homogeneous mixture of a metal with another metal or non-metal, e.g. solder is an alloy of lead and tin (Pb and Sn). Stainless steel, solder, brass, bronze, bell metal etc.

Uses of alloys :

• For increasing hardness: Iron is mixed with carbon to form stainless steel which is harder than iron. Copper is mixed with gold and lead is mixed with silver to make them hard. Duralium is an alloy made from aluminium and is very hard.
• Increasing strength: Steel, Duralium are hard as well as strong.
• Preventing Corrosion: By making stainless steel an alloy of iron, which do not get rusted.
• To produce sound: Bell metal is an alloy of copper and tin used to produce loud sound.
• To lower melting point: An alloy of Bismuth, tin and lead has low melting point.
• Moulding: Bronze and type metal.
• For change in colour: Aluminium bronze is an alloy of copper and aluminium is of golden colour.
• Domestic uses: Alloys are used in homes, factories, offices etc. e.g. utensils, almirahs, fans, refrigerators elements etc. are made up of alloys.

Question 10.
Explain the activity series of metals.
Answer:
All metals have different rates of activity. Some metals like sodium, potassium and calcium etc. are highly reactive. These metals combine with oxygen to form oxide and react with hydrogen to form hydrides. Some metals are compratively less reactive e.g. iron, zinc etc. Some metals are least reactive e.g. gold, silver. Reactivity of metals depends on their ability to lose electrons, Metals are arranged in a list in decreasing rate of their activity.

Metals which are above hydrogen are more reactive and those below hydrogen are lower in reactivity and are found in free state. In this series potassium is the most reactive metal in this series.

Short Answer Type Questions

Question 1.
Name two metals which are good conductors of heat and electricity. Name metals which are highly and least conducting with reference to heat.
Answer:
Copper and aluminium are good conductors of electricity and heat. Silver is very good conductor of heat whereas lead is not a good conductor of heat.

Question 2.
Define ductility with example.
Answer:
Property of drawing thin wires from a metal is called ductility. Gold is the highest ductile metal. We can draw 2 km long wire from 18 carat gold.

Question 3.
What is electrical conductivity? Name the metals which have the highest conductivity, less than this and the lowest conductivity.
Answer:
It is the ease with which electric current can flow through a metal. Those metals which offer very low resistance to the flow of current they have high conductivity. Silver, copper are very good conductors of current then comes gold, aluminium and tungsten. Lead and iron have least conductivity i.e., they offer very high resistance to the flow of current.

Question 4.
Which property of metals give them characteristic chemical properties?
Answer:
Metals form positive ions by loosing electrons. This property of formation of ions by the metals give them characteristics chemical properties, e.g., Mg form Mg ion by loosing two electrons :
Mg → Mg²⁺ + 2e^–

Question 5.
Ionic compounds are found in which state? Comment on the melting and boiling point of ionic compounds.
Answer:
Compounds which are formed by the transfer of electrons from metals to Non¬Metals are called ionic or electrovalent compounds e.g., NaCl, LiCl, CaCl₂, CaO, MgCl₂. Ionic compounds have very high melting and boiling points because a large amount of energy is required to break the strong inter-ionic attractions.

Question 6.
What is difference between minerals and ores?
Answer:

Sr. No. Minerals	Ores
1. Those natural occuring substances, which contain metals in the form of compounds.	1. These are the minerals from which metals can be extracted easily and cheaply.
2. In many of the minerals percent age amount of metals is large and in some it is less.	2. In all the ores, percentage amount of metals is enough.
3. In some minerals there are so many impurities which create difficulty in the extraction of metals.	3. Ores do not have such problematic impurities.
4. All the minerals can not be used for extracting metals. All the minerals are not ores.	4.         All the ores can be used to extract metals.

Question 7.
How are the metals extracted, which are at the top of reactivity series?
Answer:
Metals which are towards the top of reactivity series are sodium, calcium, magnesium, aluminium. There are very reactive. These metals can not be obtained by heating them with carbon. These have more affinity towards oxygen, therefore these are extracted by electrolytic reduction. Sodium, magnesium and calcium are obtained by the electrolysis of their molten chlorides. Metals got deposited at cathode and chorine is liberated at anode.
At cathode : Na⁺ + e^– → Na
At anode : 2Cl^– → Cl₂ + 2e^–

Aluminium is obtained by the electrolytic reduction of aluminium oxide.
At cathode ; Al³⁺ + 3e^– → Al

Question 8.
How the metals, which are in the middle of the activity series extracted?
Answer:
Metals which are in the middle of the activity series are iron, zinc, lead, copper etc. These are found in the form of sulphides or carbonates. It is easy to obtain metals from their oxides compared to sulphides or carbonates. Therefore before extraction metal sulphide or carbonates are converted into their oxide. Sulphide ores are converted into metal oxides by heating in the presence of air. This is known as roasting. Carbonate ores are heated in limited supply of air to convert them into oxides. This is known as calcination. Following reactions take place during roasting and calcination of zinc.


Then by using carbon as reducing agent, metal is extracted from metal oxide, e.g. when Zinc oxide is heated with carbon it gets reduced to give zinc.

In addition to using carbon for reduction, displacement reaction can be used to extract metals. More reactive metals like sodium, calcium, aluminium etc. can be used as reducing agents because these can displace atoms which are below them in the reactivity series. For example, when mangnese dioxide is heated with aluminium powder then following reaction takes place.

Question 9.
How will you extract metals which are low in the activity series?
Answer:Metals low in the activity series are less reactive and can be obtained from metal oxides simply by heating. Cinnabar (Hgs) an ore of mercury (Hg) when heated change to mercuric oxide (HgO), on heating it further it is reduced to mercury.

Question 10.
Explain the reactions of metals with water.
Answer:
On reacting with water, metals form metal oxide and produce hydrogen. These dissolve in water to form metal hydroxide. But all metals do not react with water.

Metals like sodium and Potassium react with cold water, vigorously. The reaction of sodium and Potassium is very vigorous and exothermic that hydrogen produced starts burning simultaneously.
2K (s) + 2H₂O (l) → 2KOH (aq) + H₂(g) + heat
2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂(g) + heat

Reaction of calcium with water is slow. Heat produced in this reaction is not enough to burn the hydrogen produced in the reaction.
Ca (s) + 2H₂O(l) → Ca (OH)₂ + H₂(g)

Metals like iron, aluminium, zinc etc. do not react with cold water and not even with hot water. But they react with steam to form metal oxide and produce, hydrogen.
2Al(s) + 3H₂O(g) → Al₂O₃(S) + 3H₂(g)
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
Metals like lead, copper, silver and gold etc. do not react with water.

Question 11.
How do metals react with :
1. Oxygen
2. Dilute acids
3. Chlorine
4. Hydrogen.
Answer:
I. Reaction of metals with oxygen: Metals combine with oxygen to form metal oxides. Metal atoms lose their loosely bound electrons to form positive ions where as oxygen atoms gain electrons to form negative oxide ions. These metal oxide are basic in nature. Since all metals have different level of reactivity therefore they combine with oxygen at different temperatures.
1. Na and K Combine with oxygen at normal temperature to form oxides which dissolve in water to form hydroxide.
4 Na (s) + O₂(g) → 2Na₂S(s)
Na₂O(s) + H₂O → 2NaOH (or)

2. If magnesium is burned in air it forms magnesium oxide.
Mg → Mg²⁺ + 2e-
O + 2e^– → O^2-
Mg²⁺ + O^2- → MgO

3. Copper and iron combine with oxygen at high temperature in dry air.

II. Reaction of metals with dilute acids. Metals reacts with dilute acids to produce hydrogen gas. Rate of reactivity is different.
1. Na, K, Zn, Mg, Fe etc. are reactive in decreasing order.
2Na + HCl → 2NaCl + H₂ ↑
Mg + 2HCl → MgCl₂ + H₂↑
Zn + H2SO₄ → ZnSO₄ + H₂↑

2. Dilute nitric acid reacts with metals like Cu, Ag, Pb, Hg to form NO (nitrogen oxide).
Cu + 8HNO₃ → 3Cu (NO₃)₂ + 2NO + 4H₂O
3Ag + 4HNO₃ → 3AgNO₃ + NO + 2H₂O

3. Dilute nitric acid reacts with Mg and Mn to produce hydrogen gas.
Mg + 2HNO₃ → Mg (NO₃)₂ + H₂ ↑

4. Gold and platinum do not react with dilute acids.

III. Reaction of metals with chlorine. Metals combines with chlorine to form electrovalent chlorides.
Ca + Cl₂ → CaCl₂

IV. Reaction of metals with hydrogen. Reactive metals like Na, K, Ca etc. react with hydrogen to form hydrid.
2Na + H₂ → 2NaH
Ca + H₂ → CaH₂

V. Reaction of metals with water:
1. Water at normal temperature react with Na, K and Ca to liberate hydrogen gas.
2Na + 2H₂O → 2NaOH + H₂ ↑
Ca + 2H₂O → Ca (OH)₂ + H₂ ↑

2. Mg, Zn and Fe react with boiling water to form oxide.
Mg + H₂O → MgO + H₂ ↑
3Fe + 4H₂O → Fe₃O₄ + 4H₂ ↑

Question 12.
What is roasting? When do you use it?
Answer:
Roasting. After enrichment of ore, it is heated in the presence of dir, this process is called roasting sulphides or carbonates of some metals are converted into oxides, because extraction of metal is easy from oxides. Carbonates and sulphides of zinc and lead are converted into oxides by roasting.

Question 13.
If a copper plate remains immersed in silver nitrate solution for some time then what happens? Write the ionic equation for the reaction.
Answer:
Copper is more reactive than silver. Copper will displace silver from the solution and silver gets deposited on copper. Colour of the solution becomes blue.

Question 14.
Copper sulphate solution is stored in an iron container. After some days holes were seen in the container. Write the reaction. Explain the reaction on the basis of activity series.
Answer:
Iron is more reactive than copper and is placed before copper in the activity series. Therefore iron can displace copper from copper sulphate solution, due to this reaction holes were seen in the container.
CuSO₄ + Fe → FeSO₄ + Cu
Cu²⁺ (aq) + Fe(s) → Fe²⁺ (aq) + Cu(s)
Thus iron displaced copper.

Question 15.
Why copper becomes green if left open in air. Why?
Answer:
Copper reacts with moist carbon dioxide which is present in air. This makes its surface dull and a green layer is seen on the surface of copper. This green substance is copper carbonate.

Question 16.
What is 24 carat gold?
Answer:
Pure gold is called 24 carat gold. It is very soft. It can be used to make ornaments. Small amount of silver or copper is mixed with it to make it harder. In our country usually 22 carat gold is used to make ornaments. This means 22 pure gold is mixed with 2 parts of copper or silver.

Question 17.
Which process is used for the enrichment of sulphide ore. Explain in brief two steps involved in the extraction of metal from enriched sulphide ore.
Answer:
Sulphide ore is finely grounded to get powder. This is then enriched by using ‘Froth floation process’.

Steps involved in the extraction of metal from enriched sulphide ore :
1. Roasting: Enriched ore is heated in the presence of air to get oxides. This process is called roasting.

2. Reduction. Oxide of the enriched ore is heated with reducing agent to extract the metal.

Question 18.
Give differences :
(i) Hydraulic washing and liquation.
Answer:

Hydraulic Washing	Liquation
1. This process is used for concentration of an ore.	1. The process is used for refining of metals.
2. Ore is washed with washing.	2. This is used for refining metal having low melting points.

(ii) Electrolytic reduction and reduction by carbon.
Answer:

Electrolytic reduction	Reduction by carbon
1. Here cathode acts as reducing agent. It converts metal ions into metals by providing electrons.	Carbon is used as reducing agent.
2. This method is used to reduce the salts of highly reactive metals.	2. This method is used to reduce the oxides of metals which are in the middle of activity series.

Question 19.
An alloy of yellow’ colour is made up of two metals A and B. When this alloy was dipped in dilute sulphuric acid, a layer dissolved in acid and formed colourless solution. B did not dissolve in it and the surface of alloy attained red brown colour. What is A and B?
Answer:
Yellow coloured alloy is brass which is mixture of zinc and copper. In this A is zinc and B is copper.
Zn + H₂SO₄ → ZnSO₄ + H₂

Question 20.
Sulphur dioxide (SO₂) gas is produced when a certain ore is heated. Write the method involved in the extraction of metal from this ore.
Answer:
SO₂ gas is produced when copper pyrites an ore of copper is heated.

Following steps are involved in the extraction of metal from this ore :
1. Ore is ground to get powder. It is mixed with water and pine oil. Compressed air is blown to separate impurities. This way ore gets enriched, this method is called froth floatation method.

2. Now the enriched ore is roasted. A part of CuS converts to CuO

Copper is in liquid state and is purified by electric refining.

3. Electrical refining. In this process impure copper rod is taken as anode and pure copper plate is taken as cathode. Electric current is passed through copper sulphate solution in the presence of acid

Question 21.
What is Thermite process? Write its uses.
Answer:
Some displacement reactions are highly exothermic. The quantity of heat produced is so high that metals obtained are in molten state. When Iron (III) oxide (Fe₂O₃) reacts with aluminium then a large amount of heat is produced.
Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + heat

This is known as thermite process. This process is used to weld the rails and to join the cracks in machines.

Question 22.
Give five uses of non-metals.
Answer:

• Hydrogen is used in the preparation of vegetable oil.
• Carbon is an important non-metal which is main constituent of vitamins, proteins, carbohydrates, enzymes etc. Graphite is used as an electrode in various cells.
• Nitrogen is used in ammonia, Nitric acid and fertilizers. Its presence in air controls the rate of combustion.
• Presence of oxygen is the base of our life. Combustion is also possible in the presence of oxygen.
• Sulphur is used in many medicines and is also used to make explosives.

Question 23.
Differentiate Roasting and Calcination.
Answer:

Roasting	Calcination
1. Roasting is used for sulphide ores.	1. Calcination is used for carbonate and hydrated ores.
2. Ore is heated in the presence of air.	2. Ore is heated in the absence of air.
3. SO2 gas is produced.	3. CO2 gas is produced.

Question 24.
How is ionic compound sodium chloride, forms from sodium and chlorine?
Answer:
Sodium and chloride ions are oppositely charged and thus attract each other
They are bound together by strong electrostatic force of attraction and exist in the form of sodium chloride (NaCl). Sodium chloride does not exist as a molecule but as a set of ions :

Question 25.
Ionic compounds are insulators when in solid state whereas when in aqueous solution they become conductors. Why?
Answer:
There exist a strong force of attraction between positive and negative ions of the ionic compounds, due to which these compounds are solid and hard. Due to their firm and rigid structure ions cannot move. But in molten state or in aqueous solution the force between opposite ions become weak and the ions can move freely. Therefore electricity can pass through ionic compounds when in liquid form.

Question 26.
What is aqua regia? Explain.
Answer:
Aqua regia is a mixutre of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3 : 1. It can dissolve gold where no single acid can do this. Aqua regia (Latin word for Royal water) is highly corrosive and fuming liquid. It can also dissolve platinum.

Question 27.
Give two main ores of aluminium. Also give two alloys of aluminium.
Answer:
Two ores of aluminium are :

1. Bauxite, Al₂O₃. 2H₂O
2. Cryolite, Na₃ (AlF₆).

Two alloys of aluminium are :

1. Duralium
2. Magnalium.

Question 28.
Give uses of pure metals.
Answer:

• Copper and aluminium wires are used in the transmission of power (electricity).
• Utensils, Machines etc. are made up of iron, aluminium and copper.
• Gold and silver are used to make ornaments, these are also used in sweets in the form of silver foil.
• Metals like cadmium, titanium, zinconium etc. are used in nuclear energy and space science projects.
• Aluminium foil is used to wrap eatables.
• Titanium and its alloys are used in airplane, airplane structure and engine, chemical reactor.
• Metals are used in broken bones and body parts.

Question 29.
Which gas is produced, when reactive metals come in contact with dilute hydrochloric acid? Write the chemical reaction between iron and dil. H₂SO₄.
Answer:
When reactive metals come in contact with dil. hydrochloric acid then (H₂) hydrogen gas is produced.
Hydrogen gas is produced when iron reacts with dil. H₂SO₄.
Fe + H₂SO₄ → FeSO₄ + H₂ ↑

Question 30.
What is the function of cryolite in the electrolytic reduction of alumina?
Answer:
Cryolite has two functions in the extraction of aluminium :

• To reduce the melting point of alumina.
• Alumina is bad conductor of electricity on mixing cryolite (Na₂AlF₃), Al²⁺ ions are produced from alumina.

Question 31.
How do iron and aluminium react with water?
Answer:
Aluminium and iron do not react with cold or hot water. But react with steam to form metal oxide and hydrogen.
2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g)
3Fe(s) + 3H₂O(g) → Fe₃O₄(s) + 3H₂(g)

Question 32.
What happen when :
(i) Iron oxide is heated with coke?
Answer:
Iron oxide is readuced to iron.

(ii) Magnesium is treated with dilute sulphuric acid?
Answer:
Hydrogen is produced

(iii) Zinc is added to blue vitriol solution?
Answer:
Blue colour of solution gradually faders away

Question 33.
What is rust? Explain it with the help of a chemical reaction.
Answer:
If iron is left open in moist air, a brown layer is produced on its surface. This brown coloured layer is of Ferric oxide and ferric hydroxide. This is called rust. This makes iron weak.
4Fe + 3O₂ + 3H₂O → Fe₂O₃ + 2Fe(OH)₃

Question 34.
Write names of main alloys and their constituents?
Answer:

Alloys	Constituents	Uses
1. Steel	Iron, carbon	used in airplanes, buildings vehicles etc.
2. Stainless steel	Iron, Carbon, Chromium	utensils, machine parts, knife, blade, food and milk industry, nuts, bolts, taps etc.
3. Brass	Copper, Zinc	utensils, idols, airplanes, medals, steam driven train parts etc.
4. Bronze	Copper, tin	utensils and other apparatus.
5. Solder	Lead, tin	For joining/welding electric wires.
6. German Silver	Copper, Nickel, zinc	Airplane wings, utensils used in kitchen of airplanes and other mate­rials.
7. Bell metal	Copper,tin	For making bells.
8. Duralium	Aluminium, copper magnesium and mangnese in very small amount.	In airplane
9. Magnoleum	Aluminium, magnesium	Light weight tools and cheap utensils.
10. Gun metal	Copper, tin, zinc	For making gears of vehicles and machines.

Question 35.
Write the names of metals found in Bronze and Duralium, give uses of these alloys.
Answer:
Bronze. It is 90% copper and 10% tin. It is used in idols, medals, coins and vessels used for cooking food.
Duralium. It consists of 95% aluminium, 4% copper, 0.5% magnesium and 0.5% manganese. It is used in aeroplanes, space crafts, kitchen vessels.

Question 36.
What is rust? What is its chemical formula?
Answer:
When iron is left open in air, then a layer of iron oxide is formed on the surface of iron. This brown matter is rust. It corrodes the metal. Its chemical formula is Fe₂O₃. xH₂O.

Question 37.
What are metals?
Answer:
The elements which are on the left and in the middle of the periodic table and have metallic lustre are called metals. These are usually ductile, malleable, good conductor of electricity and heat, hard and have high density. They form basic oxides. Examples of metals are gold, iron, silver, copper, platinum etc.

Question 38.
What is ihe reason of catching fire by potassium and sodium on their own?
Answer:
Potassium and sodium reacts with water vigorously and violently. The reaction is very violent and highly exothermic that hydrogen produced in the reaction catches fire on its own.

Question 39.
Observe the figure given below and name the gas produced. Also give the chemical equation.

Answer:
Hydrogen gas is produced

Question 40.
What is indicated by the following figure?
Or
With the help of a labelled diagram prove that both oxygen/air and water are necessary for rusting of iron.

Answer:
Both air and moisture are required for rusting of iron.

Question 41.
Why the substance obtained by mixing small amount of carbon in iron is used largely for various purposes?
Answer:
When small amount of carbon is mixed with iron it changes to steel. This is stronger than iron. It can be used in ships, vehicles, dams.

Question 42.
Write a chemical equation for the reaction taking place in the test tube. How does the colour of solution change? What is change in colour of iron nails?

Answer:

The colour of the solution changes from blue to light green. The colour of Iron nails changes from grey to brown.

Very Short Answer Type Questions

Question 1.
Give one example of metal which is liquid at room temperature.
Answer:
Mercury.

Question 2.
Name one metal and one non-metal which is liquid at room temperature.
Answer:
Metal-Mercury.
Non-Metal—Bromine

Question 3.
Name one non-metal which has bright lustre.
Answer:
Iodine.

Question 4.
Name one non-metal which does not have bright.
Answer:
Phosphorus.

Question 5.
Which of the following metal are liquid at body temperature (37° C): Gallium, Magnesium, Caesium, Aluminium.
Answer:
Gallium and Caesium.

Question 6.
Name one non-metal which is a good conductor of electricity?
Answer:
Graphite (Carbon).

Question 7.
Arrange the following metals in the decreasing order of reactivity,
Fe, Zn, Cu, Na, Ag.
Answer:
Na > Zn > Fe > Cu > Ag.

Question 8.
Out of Sodium, Calcium, Aluminium, Copper and Magnesium name the metal which reacts with
(i) Boiling water
Answer:
Magnesium

(ii) Steam.
Answer:
Copper.

Question 9.
Sodium metal is kept under kerosene oil, why?
Answer:
This is because sodium reacts with moist air as well as water.

Question 10.
A non-metal X, exists in two forms Y and Z. Y is the hardest substance and Z is a poor conductor of electricity. What are X, Y and Z?
Answer:
Y = Diamond Z = Graphite X = Carbon
Y and Z are allotropic forms of carbon.

Question 11.
An element, A form two oxides AO and AOa. AO is neutral and AO₂ is acidic : Indicate whether A is metal or non-metal.
Answer:
A is non-metal.

Question 12.
Name the reaction to convert metal into its oxide .
Answer:
Oxidation.

Question 13.
Ionic solids have high melting points, why?
Answer:
In ionic solids, there are strong electrostatic forces of attraction between the oppositely charged ions and a large amount of energy required to overcome these forces.

Question 14.
An element X reacts with oxide to form oxide, X₂O which dissolves in water and turns red litmus solution blue. Give the nature of oxide and indicate X is metal or non-metal.
Answer:
X₂O is basic. X is metal.

Question 15.
What is the nature of metal oxides?
Answer:
Basic.

Question 16.
Name two noble metals.
Answer:
Gold and platinum.

Question 17.
Name an ore of mercury.
Answer:
Mercury sulphide (Hgs).

Question 18.
Name two metalloids.
Answer:
Arsenic, antimony.

Question 19.
Metals lose lustre when placed in air, why?
Answer:
This is because their surfaces are covered with oxides, carbonates or sulphide layer’s .

Question 20.
Name two metals which can be cut with a knife.
Answer:
Sodium and potassium.

Question 21.
Why do metals aquire different shapes?
Answer:
This is due to malleability and ductility of metals.

Question 22.
Name the metal which is poor conductor of heat.
Answer:
Lead.

Question 23.
Name the metal which offers resistance to the flow of electricity.
Answer:
Mercury.

Question 24.
Which of the following metals can be drawn into wires?
Answer:
Cu, Al, Fe, Pb.

Question 25.
Name four non-metals which are solid at room temperature.
Answer:
Carbon, Sulphur, Phosphorous, and iodine.

Question 26.
Name the elements which are present in abundance in earth’s crust.
Answer:
Oxygen and silicon.

Question 27.
What are alkalies? Give one example.
Answer:
Alkali. It is a metal hydroxide soluble in water Example : Sodium hydroxide (NaOH).

Question 28.
Name two amphoteric oxide.
Answer:

1. Aluminium oxide (Al₂O₃)
2. Zinc Oxide (ZnO)

Question 29.
What happens when magnesium is heated to ignition temperature?
Answer:
Magnesium burns with white light producing magnesium oxide.

Question 30.
Name the metal which does not react with dil. HCl.
Answer:
Copper.

Question 31.
Name two metals which react with hydrogen.
Answer:
Sodium and potasium.

Question 32.
Give the reaction when a piece of Calcium reacts with water.
Answer:
Ca + 2H₂O → Ca (OH)₂ + 4H₂.

Question 33.
Give the reactions when red hot iron reacts with steam.
Answer:
Ca + 4H₂O → Fe₃O₄ + H₂.

Question 34.
Why is zinc oxide called amphoteric oxide?
Answer:
This is because zinc oxide reacts with both acid as well as base.

Question 35.
The metals Na, K and Ca react with hydrogen to form hydroxide but other metals don’t, why?
Answer:
This is because Na, K and Ca are highly reactive metals.

Question 36.
Give the reactions which occur when zinc plate is added to copper sulphate solution.
Answer:
Zn + CuSO₄ → ZnSO₄ + Cu.

Question 37.
Out of the metals, Na, Cu, Au, which is
(i) Most reactive and
Answer:
Most reactive metal-Sodium (Na)

(ii) Least reactive?
Answer:
Least reactive metal-Gold (Au).

Question 38.
Arrange the following metals in the decreasing order of reactivity, Zinc, Mercury and Aluminium.
Answer:
Al < Zn < Hg.

Question 39.
Name two metals which occur in free state in nature.
Answer:
Gold and Platinum.

Question 40.
Define corrosion of metals.
Answer:
It is the interaction of surface of metal with air and moisture forming a layer of oxide, halide or carbonate layer on its surface.

Question 41.
Name a metal which undergoes corrosion in air.
Answer:
Iron.

Question 42.
Name two metals which are not corroded easily.
Answer:
Gold and silver.

Question 43.
Why does copper utensils turn green on exposure to air?
Answer:
Copper reacts with oxygen, carbon dioxide and moisture to form a green coloured compound (basic copper carlxmate):

Question 44.
Name two metals which are both malleable and ductile.
Answer:

1. Copper
2. Aluminium.

Question 45.
Name the most abundant metal in the earth’s crust.
Answer:
Aluminium.

Question 46.
Name the metal that gives a green coating when exposed to moisture.
Answer:
Copper.

Question 47.
Which is the most lightest metal known to us?
Answer:
Lithium.

Question 48.
Name two metals which occur in free state in nature.
Answer:

1. Gold
2. Platinum.

Question 49.
Name one of the most common ore of aluminium.
Answer:
Bauxite (Al₂O₃. 2H₂O).

Question 50.
What is an amalgam?
Answer:
An amalgam is an alloy of mercury with some other metals.

Question 51.
Name two metals which :
(a) readily burn in air an
Answer:
Metals which readily burn in air are :

1. sodium
2. magnesium.

(b) do not burn.
Answer:
metals which do not burn readily in air are :

1. Copper
2. iron.

Question 52.
Name the metal which is best conductor of electricity.
Answer:
Silver.

Question 53.
Name one metal which reacts with cold water.
Answer:
Sodium.

Question 54.
Name one metal
(i) more reactive than hydrogen and
Answer:
Sodium

(ii) less reactive than hydrogen.
Answer:
Silver.

Question 55.
Write the chemical name of any one compound ore of sulphur.
Answer:
Zinc sulphide (ZnS).

Question 56.
Name the metal used in galvanisation of iron.
Answer:
Zinc.

Question 57.
The metal which is found in nature in the free state is
Answer:
Gold and Platinum.

Question 58.
What chemical process is used for obtaining a metal from its oxide?
Answer:
Reduction process.

Question 59.
Which metals do not corrode easily?
Answer:
The metals which are not attacked by air and moisture don’t corrode easily.

Multiple Choice Questions :

Question 1.
The non-metal which is liquid at room temperature is:
(A) Chlorine
(B) Bromine
(C) Fluorine
(D) Iodine.
Answer:
(B) Bromine

Question 2.
Most reactive metal is:
(A) Na
(B) Mg
(C) Au
(D) K
Answer:
(D) K

Question 3.
The property due to which metals can be beaten into sheets is :
(A) Malleability
(B) Ductility
(C) Metallic lustre
(D) Hardness.
Answer:
(A) Malleability

Question 4.
The axnphoteric oxide is:
(A) ZnO
(B) BaO
(C) K2O
(D) Na2O.
Answer:
(A) ZnO

Question 5.
Copper gets covered with green layer when exposed to air due to the formation of:
(A) CuSO₄
(B) CuCO₃. Cu(OH)₂
(C) Cu (NO₃)₂
(D) CuO.
Answer:
(B) CuCO₃. Cu(OH)₂

Question 6.
During galvanisation, the metal whose layer is deposited is:
(A) Gallium
(B) Aluminium
(C) Zinc
(D) Silver.
Answer:
(C) Zinc

Fill in the blanks:

Question 1.
Brass is an alloy of copper and ____________
Answer:
Zinc.

Question 2.
____________ is the best conductor of electricity.
Answer:
Silver.

Question 3.
All the ores are ____________
Answer:
Minerals.

Question 4.
Copper can be refined by ____________
Answer:
Electrorefining.