PSEB Notes

This PSEB 10th Class Science Notes Chapter 10 Light Reflection and Refraction will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 10 Light Reflection and Refraction

→ Light is an external physical agent which produces in us the sensation of sight.

→ When light travelling in one medium falls on the surface of another medium, the following three effects are observed:

• A part of the incident light is turned back (or reflected) into the first medium.
• Another part travels through the second medium along a changed path (i.e the fight is refracted).
• The remaining part is absorbed by the second medium.

→ Objects are always placed in front of the mirror to their left, so u (object distance) is always negative.

→ The focal length of the convex mirror is taken as positive (+) and that of the concave mirror as negative (-).

→ Magnification of a concave mirror forming real image is m = \(\frac{v}{u}\) and that of convex mirror and also a concave mirror forming virtual image is m = \(\frac{-v}{u}\).

→ All distances measured in the direction of the incident light are taken as positive and distances measured in a direction opposite to the incident ray are taken as negative.

→ The phenomenon of bending of a light ray when it travels from one medium to another medium of different optical densities is called the refraction of light.

→ When a ray of light travels from an optically rarer to an optically denser medium, it bends towards normal.

→ When a ray of light travels from an optically denser to an optically rarer medium, it bends away from normal.

→ The higher the refractive index the more is the denser medium.

→ The ratio of the sine of the angle of incidence (Sin i) to the sine of the angle of refraction (Sin r) is constant, called the refractive index of the medium.

→ The Refractive index of a medium is the ratio of the velocity of light in a vacuum to the velocity of light in a medium.

→ The lens is a portion of the transparent and refracting medium.

→ The relation between the object distance (u), the image distance (v) and the focal length (f) of a lens is called lens formula i.e. \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\)

→ The power of a lens is the reciprocal of its focal length. Its unit is dioptre.

→ Mirror: Any smooth and polished surface is called a mirror.

→ Reflection of Light: When light falls on a mirror or a polished surface then without any change in the medium it returns into the same medium along a particular direction. This phenomenon of change of path of light is called reflection.

→ Incident Ray: A ray of light coming from a source of light falling on any surface is called an incident ray.

→ Reflected Ray: After reflection, a ray of light coming back from point of incidence into the same medium is called a reflected ray.

→ Incident Point: The point on the reflecting surface where incident ray strikes is called incident point.

→ Normal: The perpendicular drawn at the point of incidence is called normal.

→ The angle of Incidence: The angle between the incident ray and the normal is called the angle of incidence.

→ The angle of Reflection: The angle between the reflected ray and the normal is called the angle of reflection.

→ Ray of Light: The straight path of light is called a ray of light.

→ Spherical Mirror: If the mirror is a part of some hollow sphere whose one surface is polished and the other surface is reflecting then such mirror is called a spherical mirror.

→ Concave Mirror: A spherical mirror whose reflecting surface is towards the centre of a hollow sphere of which the mirror is a part, is called a concave mirror.

→ Convex Mirror: A spherical mirror whose reflecting surface is away from the centre of a sphere of which the mirror is a part, is called a convex mirror.

→ Centre of Curvature: Centre of curvature of a spherical mirror is the centre of a sphere of which the mirror is a part.

→ Pole: The midpoint of a spherical mirror is called the pole of the mirror.

→ Principal Axis: An imaginary line joining the pole and centre of curvature of a spherical mirror is called the principal axis.

→ The radius of Curvature: It is the radius of a sphere of which the spherical mirror is a part.

→ Aperture: That part of the mirror from where actually reflection takes place is called the aperture of the mirror.

→ Principal Focus: It is the point on the principal axis where the rays of light coming parallel to the principal axis after reflection actually meet or appear to diverge is called the principal focus of the mirror.

→ Focal Length: The distance between pole and principal focus of spherical mirror is called the focal length of the mirror. It is usually denoted by f.

→ Magnification: The magnification of a spherical mirror is the ratio of the length (size) of the image to the length (size) of the object. It is denoted by ‘m’.

→ Refraction of Light: The change of path of light when it goes from one medium to another medium is called refraction of light.

→ Transparent Medium: Mediums like air, water, and glass through which light can pass easily are called transparent mediums.

→ Lens: A portion of transparent and refracting medium bounded by two surfaces is called the lens.

→ Power of Lens: The capacity of a lens to converge or diverge light rays is called the power of the lens. It is denoted by ‘P’.

→ Centres of Curvature of Lens: The centres of spheres of which the spherical surfaces of the lens are part, are called centres of curvature of the lens.

→ Principal Axis of Lens: The line passing through the centres of curvature of the lens, is called the principal axis of the lens.

→ Optical Centre: A point of the lens through which rays of light go undefeated, is called an optical centre.

→ Principal Focus of Lens: The point on the principal axis of the lens, where rays coming parallel to the principal axis after refraction either actually converge or appear to diverge, is called the principal focus of the lens.

This PSEB 10th Class Science Notes Chapter 9 Heredity and Evolution will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 9 Heredity and Evolution

→ Heredity: It is the transmission of genetic characters from parents to the offspring i.e., from one generation to the next.

→ Variation: The differences among the individuals of a species and also in the offsprings of the same parents are referred as a variation.

→ Every organism produce offsprings either through asexual or sexual reproduction. The individuals produced through these reproductive processes are similar but subtly different.

→ In asexual reproduction, although all the offsprings resemble each other and also to their single parent, yet very minor differences (variations) arise in them.

→ For example, if we observe a field of sugarcane we find very few variations among the individual plants.

→ The reproductive processes give rise to new individuals that are similar, but subtly different.

→ The number of successful variations is maximized by the process of sexual reproduction.

→ Inheritance from the previous generation provides both a common basic body design and subtle changes in it, for the next generation.

→ The second generation will have differences that they inherit from the first generation, as well as newly created differences.

→ Some amount of variation is produced even during asexual reproduction.

→ The selection of variants by environmental factors forms the basis for evolutionary processes.

→ A child bears all the basic features of a human being.

→ Both the father and the mother contribute practically equal amounts of genetic material to the child.

→ Mendel was the first one to keep count of individuals exhibiting a particular trait in each generation.

→ Mendel used a number of contrasting visible characters of a garden pea. Cellular DNA is the information source for making proteins in the cell.

→ A section of DNA that provides information for one protein is called the gene for that protein.

→ Plant height can also depend on the amount of a particular plant hormone. Genes control characteristics or traits.

→ Each cell will have two copies of each chromosome, one each from the male and female parents.

→ Every germ cell will take one chromosome from each pair and these may be of either maternal or paternal origin.

→ In some animals, the temperature at which fertilized eggs are kept determines whether the animals developing in the eggs will be male or female.

→ In other animals, such as snails, individuals can change sex, indicating that sex is not genetically determined.

→ Human has 23 pairs of chromosomes.

→ Women are XX, while men are XY.

→ The frequency of inherited traits changes over generations.

→ The germ cells of sexually reproducing populations are made in specialized reproductive tissue.

→ Change in non-reproductive tissues cannot be passed on to the DNA of the germ cells..

→ An individual cannot pass on to its progeny the experiences of its lifetime.

→ Charles Darwin formulated in his hypothesis that evolution took place due to natural selection.

→ We often associate Darwin solely with the theory of evolution.

→ J.B.S. Haldane, a British scientist (who became a citizen of India later), suggested in 1929 that life must have developed from the simple inorganic molecules which were present on earth soon after it was formed.

→ Some basic characteristics will be shared by most organisms.

→ The cell is the basic unit of life in all organisms.

→ Bacterial cells do not have nuclei while the cells of most other organisms do.

→ Among multicellular organisms, whether they can undertake photosynthesis or not, is an important level of classification.

→ The skeleton is inside the body or around the body is another fundamental design difference.

→ The more characteristics two species will have in common, the more closely they are related.

→ The more closely they are related, the more recently they will have had a common ancestor.

→ Non-living material must have given rise to life.

→ The characteristics in different organisms would be similar because they are inherited from a common ancestor.

→ Mammals have four limbs, as do birds, reptiles, and amphibians.

→ The wings of birds and bats are more closely related to each other.

→ The preserved traces of living organisms are called fossils.

→ If we dig into the earth and start finding fossils, it is reasonable to suppose that the fossils we find closer to the surface are more recent than the fossils we find in deeper layers.

→ The dating of fossils is done by detecting the ratios of different isotopes of the same element in the fossil material.

→ The complex organs 4vill be created bit-by-bit over generations.

→ Like the wing, the eye seems to be a very popular adaptation.

→ The structure of the eye in different organisms is different. It shows that they have separate evolutionary origins.

→ A flatworm named Planaria has very simple ‘eyes’ that are really just eye spots that detect light.

→ A change that is useful for one property to start with, can become useful later for quite a different function.

→ Feathers, for example, can start out as providing insulation in cold weather but later, they might become useful for flight.

→ The birds are very closely related to reptiles.

→ Humans have started cultivating wild cabbage as a food plant for over more than two thousand years and generated different vegetables from it by selection.

→ Changes in the DNA during cell division would lead to changes in the proteins that are made from new DNA.

→ The organisms which are more distantly related will accumulate a greater number of differences in their DNA.

→ It is not true that human beings have evolved from chimpanzees. The two resultant species have probably evolved in their own separate ways to give rise to the current forms.

→ Evolution is simply the generation of diversity and the shaping of diversity by environmental selection.

→ The tools for tracing evolutionary relationships are excavating, time-dating, and studying fossils, as well as

→ DNA sequences determination has been used for studying human evolution.

→ All humans are a single species. We all come from Africa.

→ The earliest members of the human species, Homo sapiens, can be traced in Africa.

→ The origin of man, like other species on the earth, is an event of biological evolution.

→ Genetics: The branch of biology which deals with the study of heredity and variation is called genetics.

→ Heredity: The transmission of characters from generation to generation is called heredity.

→ Gene: The basic unit of heredity which transmits the traits into the next generation.

→ Sex chromosome: The pair of chromosomes which decide the sex of male and female.

→ Homologous chromosome: The pair of chromosomes each from mother and father together is called a homologous chromosome.

→ Autosomes: The chromosomes other than sex chromosomes are autosomes.

→ Evolution: The slow and continuous process of changing organisms from simple to complex form is called evolution. In simple words descend with modification.

→ Homologous organs: The organs have the same origin and basic structure but are adapted to perform various functions.

→ Analogous organs: The organs have a different origin and basic structures but perform the same function.

→ Transgenic organism: The organism produced by the introduction of foreign DNA or genes.

→ Fossils: The remains of dead animals in earth strata are called fossils.

→ Haploid: The single set of chromosomes obtained from one parent.

→ Nucleotide: A molecule made up of nitrogen base, sugar, and phosphate.

→ Chromatid: When the chromosomes divide into two each part is called a chromatid.

→ Vestigial organs: Organs in our body having no functional importance are called vestigial organs.

→ Genetic drift: The effect on the genetic continuation in a population due to the death of organisms or immigration is called genetic drift.

→ Variations are differences between young one of the same parent: They differ from their parents.

→ Variations arise due to inaccuracies in DNA replication in asexually reproducing organisms.

→ Offsprings: Young ones produced as reproduction are ailed offsprings.

→ Genotype: The internal genetic constitution of an organism is termed genotype. The environment has no effect on it.

→ Phenotype: It refers to externally visible characters of an organism. It is the net result of interactions between genotype and environment. Individuals of the same genotype breed alike are termed phenotype.

→ Recessive traits: An allele (gene) that is not expressed phenotypically when present in heterozygous conditions.

→ Speciation: The origin of species is termed speciation.

→ Acquired characters: The characters acquired during a lifetime are ailed acquired characters.

→ Life: Life is the power that an organism possesses to maintain and reproduce itself.

→ Natural selection: According to Darwin the individual with special traits survive and multiply while others perish is called natural selection.

This PSEB 10th Class Science Notes Chapter 8 How do Organisms Reproduce? will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 8 How do Organisms Reproduce?

→ The phenomenon of the formation of new individuals by the existing ones is called reproduction.

→ Reproduction is a means of the perpetuation of the species, and also a method of their multiplication.

→ Reproduction, unlike other life processes, is not essential to maintain the life of an individual organism.

→ Reproduction is the formation of similar organisms with the same body design, due to information of inheritance. (DNA or RNA).

→ Reproduction involves the creation of a DNA copy and additional cellular apparatus by the cell involved in the process.

→ DNA copies formed are not identical and have some variations but if variations are drastic then-new DNA copies cannot work.

→ All organisms reproduce. The reproducing organisms create new individuals that look very much like themselves.

→ The chromosomes in the nucleus of a cell contain information for the inheritance of features from parents to the next generation in the form of DNA (Deoxyribose Nucleic Acid) molecules.

→ The DNA in the cell nucleus is the information source for making proteins. Cells use chemical reactions to build copies of their DNA.

→ No biochemical reaction is absolutely reliable. Therefore, the process of copying the DNA will have some variations each time.

→ Some of the variations might be so drastic that the new DNA copy cannot work with the cellular apparatus it inherits. Such a newborn cell will simply die.

→ The inbuilt tendency for variation during reproduction is the basis for evolution.

→ If a population of reproducing organisms were suited to a particular niche and if the niche were drastically altered, the population could be wiped out.

→ If the water temperature increases by global warming, most of the bacteria living in temperate waters would die.

→ In unicellular organisms, cell division or fission leads to the creation of new individuals.

→ Many bacteria and protozoa simply split into two equal halves during cell division.

→ In Leishmania (which causes kala-azar), binary fission occurs in a definite orientation of the body.

→ The malarial parasite, Plasmodium, divides into many daughter cells simultaneously by multiple fission.

→ Yeast can produce small buds that separate and grow into new individuals.

→ Multicellular organisms have more complex ways of reproduction.

→ Hydra and Planaria can be cut into any number of pieces and each piece grows into a complete organism. This is known as regeneration. It is carried out by specialized cells.

→ Organisms such as Hydra use regenerative cells for reproduction in the process of budding.

→ There are many plants in which parts like the roots, stems, and leaves develop into new plants under appropriate conditions.

→ The methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes are used for agricultural purposes.

→ Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds.

→ Such methods also make possible the propagation of plants such as banana, orange, rose and jasmine that has lost the capacity to produce seeds.

→ In tissue culture, new plants are grown by taking tissue or cells from the growing tip of a plant.

→ This technique is commonly used for ornamental plants.

→ The hyphae of Rhizopus grow on the bread. They have sporangia, which contain cells or spores, which can eventually develop into new Rhizopus individuals.

→ In sexual reproduction, both sexes, males and females, are needed to produce new generations.

→ Combining variations from two or more individuals would create new combinations of variants.

→ As organisms become more complex, the specialization of tissue increases.

→ The motile germ cell is called the male gamete (pollen) and the germ cell containing the stored food is called the female gamete (ovule).

→ The reproductive parts of angiosperms are located in the flowers.

→ The flower may be unisexual (papaya, watermelon) when it contains either stamens or carpels or bisexual (Hibiscus, mustard) when it contains both stamens and carpels.

→ The ovary contains ovules and each ovule has an egg cell.

→ The fusion of the germ cells or fertilization produces the zygote.

→ The transfer of pollen from one flower to another is achieved by agents like wind, water, or animals.

→ After fertilization, the zygote divides several times to form an embryo within the ovule.

→ The seed contains the future plant or embryo which develops into a seedling under appropriate conditions. This process is known as germination.

→ Humans use a sexual mode of reproduction.

→ As adolescence starts, there are some changes taking place that are different among boys and girls. These do not happen all at the same time in one person, nor do they happen at an exact age.

→ The period of adolescence is called puberty.

→ The male reproductive system consists of portions that produce the germ cells and other portions that deliver the germ cells to the site of fertilization.

→ The formation of germ cells or sperms takes place in the testes.

→ In addition to regulating the formation of sperms, testosterone brings about changes in appearance seen in boys at the time of puberty.

→ The female germ cells or eggs are made in the ovaries.

→ The fertilized egg, the zygote, gets implanted in the lining of the uterus and starts dividing.

→ The embryo gets nutrition from the mother’s blood with the help of a special tissue called the placenta.

→ Since the ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilized egg.

→ If the egg is not fertilized, the uterus lining slowly breaks and comes out through the vagina as blood and mucus. This cycle takes place roughly every month and is known as menstruation. It usually lasts for about two to eight days.

→ The process of sexual maturation is gradual.

→ Gonorrhea and syphilis and viral infections such as warts and HIV-AIDS are sexually transmitted diseases.

→ The sexual act always has the potential to lead to pregnancy.

→ Many mechanical, hormonal, and surgical methods are used to avoid pregnancy.

→ Pre-natal sex determination has been prohibited by law.

→ Because of reckless female foeticides, the child sex ratio is declining at an alarming rate.

→ Population explosion is raising problem in our country.

→ Birth control is an attempt to control the number of births in a family so that a couple may not have more children than required.

→ Physical barriers include the use of condoms, diaphragm, and cervical caps.

→ Chemical methods include the use of specific drugs by females i.e. oral pill and vaginal pill.

→ The use of IUCD (Copper-T) is very effective.

→ Surgical methods include vasectomy and tubectomy.

→ The communicable diseases occurring due to sexual contact are called sexually transmitted diseases such as gonorrhea, syphilis, and AIDS.

→ Reproduction: It is the process of producing new organisms by existing organisms of a species.

→ Sexual reproduction: The production of offspring by the fusion of male and female gametes is called sexual reproduction. It is biparental.

→ Asexual reproduction: The production of progeny without the fusion of male and female gametes is called asexual reproduction. It is uniparental.

→ Fission: The division of an organism into two or more individuals is called fission.

→ Budding: The process of development of an outgrowth due to repeated cell division at one specific site which grows into a tiny individual is called budding.

→ Vegetative propagation: The process of development of the new individual from any part of the body is called vegetative propagation.

→ Grafting: The technique of joining the different parts of two different plants to grow into one plant.

→ Unisexual: When the male and female are separate individuals, they are called unisexual.

→ Bisexual/Hermaphrodite: The organisms having male and female in a single individual are called bisexual/hermaphrodite.

→ Scion: A stem piece of good quality plant is grafted to grow into a new plant is called the scion.

→ Layering: The production of a new plant by covering the leaned branches of a plant under the soil.

→ Pollination: The transfer of pollen from another to stigma.

→ Fertilization: The fusion of male and female gametes is called fertilization.

→ Syngamy: The fusion of male gamete with female gamete is called syngamy.

→ Double fertilization: When the fertilization occurs two times (with ovum and polar cell) in angiosperms the process is called double fertilization.

→ DNA Replication: Duplication of DNA molecule by copying from a molecular template of DNA.

→ Regeneration: The formation of the lost part is called regeneration.

→ Gamete: Haploid sex cell is called gamete.

→ Zygote: Diploid fertilized egg is called a zygote. If undergoes cleavage (non-motile division) to form a complete organism.

→ Sperm: Haploid male gamete is called sperm.

→ Ovum: Haploid female gamete is ailed ovum.

→ Ovule: A structure in the ovary of a seed plant that develops into a seed after fertilization.

→ Puberty: The process of becoming sexually mature.

→ Ovulation: The release of the ovum from the ovary.

→ Implantation: The fixation of the embryo in the uterus is called implantation.

→ Placenta: It is the connection between mother and embryo.

→ Parturition: The process of giving birth to foetus is called parturition.

This PSEB 10th Class Science Notes Chapter 7 Control and Coordination will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 7 Control and Coordination

→ Control and coordination are the functions of the nervous system and hormones in our bodies.

→ The responses of the nervous system can be classified as a reflex action, voluntary action, or involuntary action.

→ The nervous system uses electrical impulses to transmit messages.

→ The neuron is the functional unit of the nervous system that responds to stimuli by electrical impulses.

→ The Central Nervous System (CNS) consists of the brain and the spinal cord.

→ The brain is the highest coordinating centre of the body.

→ The nervous system gets information from our sense organs and acts through our muscles.

→ In many animals and some plants, there are some movements not connected with growth.

→ Some movements, in response to the environment, are carefully controlled. Each kind of change in the environment evokes an appropriate movement in response.

→ Living organisms must use systems providing control and coordination.

→ Specialized tissues are used to provide these control and coordination activities.

→ All information from our environment is detected by the specialized tips of some nerve cells.

→ We have generally five sense organs such as the eye, the ear, the nose, the tongue, and the skin.

→ The information is acquired at the end of the dendritic tip of a nerve cell.

→ It sets off a chemical reaction that creates an electrical impulse.

→ The nervous tissue is made up of an organized network of nerve cells or neurons.

→ ‘Reflex’ is a word we use very commonly when we talk about some sudden action in response to something in the environment.

→ Thinking is a complex activity, so it is bound to involve a complicated interaction of many nerve impulses from many neurons.

→ The thinking tissue in our body consists of dense networks of intricately arranged neurons. It sits in the forward end of the skull.

→ Nerves from all over the body meet in a bundle in the spinal cord on their way to the brain.

→ Nerves supply information to various organs of the body.

→ The reflex arcs have evolved in animals because the thinking process of the brain is not fast enough.

→ Brain and reflex arcs receive information from all parts of the body.

→ In fact, many animals have very little or none of the complex neuron networks needed for thinking.

→ The spinal cord is made up of nerves that supply information to think about.

→ The brain and spinal cord constitute the central nervous system.

→ The brain also has to send messages to muscles.

→ The brain allows us to think and take actions based on that thinking.

→ The brain has three major parts or regions, namely the fore-brain, mid-brain, and hind-brain.

→ The fore-brain is the main thinking part of the brain. It has regions that receive sensory impulses of hearing, smell, sight, and so on.

→ Many involuntary actions are controlled by the mid-brain and hind-brain.

→ All the involuntary actions including blood pressure, salivation, and vomiting are controlled by the medulla in the hind-brain.

→ The vertebral column or backbone protects the spinal cord.

→ The plants also use electrical-chemical means to convey the information from cell to cell.

→ Some tendrils are sensitive to touch.

→ Light and gravity change the directions of growing parts of the plant.

→ The directional or tropic movements can be either towards the stimulus or away from it.

→ The stimulated cells release a chemical compound, this compound would diffuse all around the original cell.

→ Hormones are used by multicellular organisms for control and coordination, show a great deal of diversity.

→ Different plant hormones help to coordinate growth, development, and responses to the environment.

→ A hormone called auxin, synthesized at the shoot tip, helps the cells to grow longer.

→ The plant hormones are gibberellins which, like auxins, help in the growth of the stem.

→ Adrenaline is a hormone secreted by the adrenal (kidney) gland in humans. It affects the heart, respiration, digestion, skeleton muscles in humans and other organisms.

→ Iodine is necessary for the thyroid gland to make the thyroxine hormone.

→ Thyroxine regulates carbohydrate, protein, and fat metabolism in the body so as to provide the best balance for growth.

→ In case of iodine is deficient in our diet, there is a possibility that we might suffer from goiter.

→ Growth hormone is one of the hormones secreted by the pituitary. As its name indicates, growth hormone regulates the growth and development of the body.

→ There is the secretion of testosterone in males and estrogen in females.

→ Insulin is a hormone that is produced by the pancreas and helps in regulating blood sugar levels.

→ Neuron: The structural and functional unit of the nervous system is called a neuron.

→ Sensory organ: The organs which sense the changes in the surrounding environment and pass on the information to the central nervous system are called sensory organs.

→ Hormone: The special chemical substances secreted by endocrine glands (ductless glands) and transported by the blood to control the body functions.

→ Phototropism: The movement of plants towards light is called phototropism.

→ Geotropism: The movement of plant roots due to the earth’s gravity is called geotropism.

→ Chemotropism: The movement of plant parts or plants due to the chemical stimulus is called chemotropism.

→ Phytohormones: These are the hormones secreted by plants to perform various functions.

→ Nastic movements: When the stimulus does not produce any movement in plants.

→ Phytochrome: These are special pigments that respond to the photoperiod.

→ Ganglion: The group of cell bodies of nerve cells is called a ganglion.

→ Reflex action: The involuntary actions towards emergency situations.

→ Reflex arc: The path through which the signal travels during reflex action is called the reflex arc.

→ Spinal cord: Nerves from all over the body meet to form a bundle/cord on their way to connect with the hindbrain is called the spinal cord.

→ Central nervous system: The brain and nerve cord together constitute the central nervous system.

→ Motor neurons: The neurons which carry the responses to the concerned organs.

→ Sensory neurons: The neurons which carry the message from sensory organs to the brain.

→ Nerve impulse: The conduction of chemical or electric signals by nerve cells is called nerve impulse.

→ Voluntary action: These are the actions that need thinking. They are performed knowingly, i.e., controlled by conscious thought. Example. Speaking to a friend, writing a letter, etc.

→ Involuntary action: These are not under the control of the will of an individual. They are automatic responses to a stimulus that is not under the voluntary control of the brain. Example. Touching a hot plate unknowingly.

→ Endocrine glands secrete the hormones directly into the blood.

→ Exocrine glands are glands with ducts that pour their secretion at the site of action.

→ Insulin is the hormone produced by β-cells of islets of Langerhans which controls sugar metabolism.

This PSEB 10th Class Science Notes Chapter 6 Life Processes will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ Visible movement is not the only defining characteristic of life.

→ Plants do not show locomotory movements, but movements occur at the molecular level.

→ Viruses are living only inside living organisms.

→ Every living organism takes food, derives energy, passes out waste material, and responds to changes within the body and environment. All these activities are collectively termed life processes.

→ These life processes are required for the maintenance of life.

→ The body needs energy which is obtained from the food that the organism eats.

→ The source of energy is called food. So there must be a process to transfer a source of energy (food) from outside to inside the body of an organism. This process is commonly called nutrition.

→ Since life on earth depends on carbon-based molecules, most of these food sources are also carbon-based.

→ Oxidizing-reducing reactions are some of the most common chemical means to break-down large molecules.

→ The process of acquiring oxygen from outside the body and using it in the process of breakdown of food sources for cellular needs is called respiration.

→ In the case of a single-celled organism, there are no specific organs for taking in food, exchange of gases, or removal of wastes because the entire surface of the organism is in contact with the environment.

→ In multicellular organisms, various body parts are specialized for the functions they perform.

→ The uptake of food and of oxygen will also be the function of specialized tissues.

→ We need energy every time for our life activities.

→ The general requirement for energy and materials is common in all organisms, but it is fulfilled in different ways.

→ The heterotrophs’ survival depends directly or indirectly on autotrophs. Heterotrophic organisms include animals and fungi.

→ The carbon and energy requirements of the autotrophic organism are fulfilled by photosynthesis.

→ Photosynthesis is the process by which autotrophs take in substances from the outside and convert them into stored forms of energy.

→ This material is taken in the form of carbon dioxide and water which is converted into carbohydrates in the presence of sunlight and chlorophyll.

→ Some of the energy derived from the food we eat is stored in our bodies in the form of glycogen.

→ The green dots are cell organelles called chloroplasts which contain chlorophyll.

→ Stomata are tiny pores present on the surface of the leaves.

→ Massive amounts of gaseous exchange take place in the leaves through these pores for the purpose of photosynthesis.

→ Since large amounts of water can also be lost through these stomata, the plant closes these pores when it does not need carbon dioxide for photosynthesis.

→ Plants take up materials like nitrogen, phosphorus, iron, and magnesium from the soil.

→ Nitrogen is an essential element used in the synthesis of proteins and other compounds.

→ The form of nutrition differs depending on the type and availability of food material as well as how it is obtained by the organism.

→ Fungi like bread moulds, yeast, and mushrooms break down the food material outside the body and then absorb it.

→ In single-celled organisms, the food may be taken in by the entire surface.

→ Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food vacuole.

→ In Paramecium, which is also a unicellular organism, the cell has a definite shape, and food is taken in at a specific spot.

→ The alimentary canal is basically a long tube extending from the mouth to the anus.

→ When we eat something we like, our mouth ‘waters’. This is actually a fluid called saliva secreted by the salivary glands.

→ The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar.

→ The stomach is a large organ that expands when food enters it.

→ The gastric glands present in the wall of the stomach release hydrochloric acid, a protein-digesting enzyme called pepsin and mucus.

→ The small intestine is the longest part of the alimentary canal.

→ Meat is easier to digest, hence carnivores like tigers have a shorter small intestine. It is the site of the complete digestion of carbohydrates, proteins, and fats.

→ The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.

→ The undigested food is sent into the large intestine where a large number of villi absorb water from this material.

→ The food material taken in during the process of nutrition is used in cells to provide energy for various life processes.

→ The respiration takes place in the presence of air (oxygen), it is called aerobic respiration.

→ The release of energy in this aerobic process is much greater than in the anaerobic process.

→ The synthesis of lactic acid in our muscles during strenuous activity causes cramps.

→ The energy released during cellular respiration is immediately used to synthesize a molecule called ATP which is the fuel for all other activities in the cell.

→ ATP is broken down to release a fixed amount of energy which can drive the endothermic reactions taking place in the cell.

→ At night, when there is no photosynthesis occurring, CO₂ elimination is the major exchange activity going on.

→ Aquatic animals that live in water need to use the oxygen dissolved in water.

→ Since the amount of dissolved oxygen is fairly low as compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that of terrestrial organisms.

→ The air passing through the nostrils is filtered by fine hairs that line the nasal passage.

→ Within the lungs, the passage divides into smaller and smaller tubes which finally terminate in balloon-like structures called alveoli.

→ The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the oxygen in the alveolar air is taken up by the blood in the alveolar blood vessels to be transported to all the cells in the body.

→ In human beings, the respiratory pigment is hemoglobin which has a very high affinity for oxygen.

→ If the alveolar surface were spread out, it would cover about 80 square meters.

→ The blood is a fluid connective tissue.

→ Blood consists of a fluid medium called plasma.

→ Plasma transports food, carbon dioxide, and nitrogenous wastes in dissolved form.

→ The heart is a muscular organ that is as big as our fist.

→ The heart has two regions; the atrium and ventricle. Ventricle has a thicker muscular wall than the atrium because the ventricle has to pump blood through the whole body.

→ Valves ensure that blood does not flow backward when the atria or ventricles contract.

→ The separation of the right side and the left side of the heart is to prevent oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body.

→ Amphibians or many reptiles have three-chambered hearts while Fishes have only two-chambered hearts.

→ Blood goes through the heart twice during each cycle in amphibians and other vertebrates. This is known as double circulation.

→ The force that blood exerts against the wall of a vessel is called blood pressure. This pressure is much greater in arteries than in veins.

→ The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.

→ Blood pressure is measured with an instrument called a sphygmomanometer.

→ High blood pressure is also called hypertension. It can lead to the rupture of an artery and internal bleeding.

→ Arteries are the vessels that carry blood away from the heart to various organs of the body. Veins collect the blood from different organs and bring it back to the heart.

→ The blood has platelet cells that circulate around the body and they plug the leaks by helping to clot the blood at these points of injury.

→ There is another type of fluid also involved in transportation. This is called lymph or tissue fluid.

→ The xylem tissue (vessels and tracheids) of the roots, stems, and leaves are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant.

→ The loss of water in the form of vapours from the aerial parts of the plant is known as transpiration.

→ The transport of soluble products of photosynthesis is called translocation and it occurs in the part of the vascular tissue known as phloem.

→ Unlike transport in the xylem which can be largely explained by simple physical forces, the translocation in the phloem is achieved by utilizing energy.

→ Excretronr-All plants and animals produce harmful substances due to a number of metabolic activities occurring in their body tissues. These harmful substances are to be eliminated from the body, otherwise, they act as toxic substances.

→ In human beings, excretory products in the form of soluble nitrogen compounds are removed by the nephrons in the kidneys.

→ Plants use a variety of techniques to get rid of waste materials that are stored in the cell vacuoles, like removing them in the falling leaves or excreted into the surrounding soil.

→ The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder, and a urethra.

→ The purpose of making urine is to filter out waste products from the blood.

→ Nitrogenous wastes such as urea or uric acid are removed from blood in the kidneys.

→ Enzymes: The bio-catalysts initiate or enhance the rate of reaction in a living system without undergoing any change in themselves. They are proteinic in nature.

→ Nutrition: It is the process by which living organisms take up nutrients from the environment and use them for the development of cells and tissues and also for energy.

→ Autotrophs: The organisms which make their food from simple substances like CO₂, water, and minerals with their own chlorophyll in the presence of sunlight are called autotrophs.

→ Heterotrophs: The organisms which cannot synthesize their own food. They depend on autotrophs for their food supply directly or indirectly. Saprophytes. The organisms which depend on dead, decaying organic matter for their nutritional requirements are called saprophytes.

→ Parasites: Those organisms which depend upon other living organisms (host) for their food and shelter are called parasites. There are two types of parasites i.e. ectoparasites (outside the body) and endoparasites (inside).

→ Holozoan: Holozoans are heterotrophs that involve the intake of solid pieces of food. Since solid food is taken in, holozoic nutrition is also called ingestive nutrition. It is found in animals and Protozoa.

→ Herbivorous: The organisms which take their food in the form of plants and plant products are called herbivorous.

→ Carnivorous: Those organisms which rely on the flesh of other organisms are called carnivorous.

→ Omnivorous: Those organisms which can feed upon plants, as well as other organisms, are called omnivorous.

→ Ingestion: The process of intake of food in the mouth is called ingestion. Digestion. The process of breakdown of complex food material into -simpler substances is called digestion.

→ Photosynthesis: The autotrophs take in CO₂ and H₂O and convert these into carbohydrates in the presence of chlorophyll and sunlight is called Photosynthesis.

→ Compensation point: In the shadow (morning and evening) when photosynthesis is very low, the CO₂ produced in respiration is equal to the CO₂ consumed in photosynthesis. This situation when the CO₂ absorption from the environment is about nil is called a compensation point.

→ Respiration: It is the process of oxidation of carbohydrates in the cells to release energy that is used by the cells for different purposes.

→ Aerobic respiration: The respiration taking place in the presence of air – (oxygen) is called aerobic respiration.

→ Anaerobic respiration: The respiration taking place in the absence of air is (oxygen) called anaerobic respiration.

→ Respiratory substrate: The substance which is oxidized during respiration is called the respiratory substrate.

→ Glycolysis: It is the metabolic pathway in the cytoplasm that converts glucose into pyruvate.

→ Anabolism: It refers to chemical reactions in which simpler substances are combined to form more complex molecules. Anabolic reactions usually require energy.

→ Catabolism: It refers to chemical reactions that result in the breakdown of more complex organic molecules into simpler substances.

→ Fermentation: Fermentation is a metabolic process that converts sugar/glucose to CO₂ and other simple carbon compounds like alcohol, lactic acid, malic acid, acetic acid, etc.

→ ATP: Adenosine triphosphate is a nucleoside triphosphate used in cells as a coenzyme often called the “molecular unit of currency” of intracellular energy transfer.

→ Stomata: These are tiny pores present on the surface of the leaves. Massive amounts of gaseous exchange take place in the leaves through these pores for the purpose of photosynthesis.

→ Breathing: The process of taking air into and expelling it from the lungs is called breathing.

→ Inspiration: The intake of oxygen from the environment into the lungs is called inspiration.

→ Expiration: The process of throwing out CO₂ from the lungs is called expiration.

→ Transpiration: The loss of water in the form of vapours from the aerial parts of the plant is known as transpiration.

→ Xylem: A continuous system of water-conducting channels reaching all parts of the plant is called the xylem.

→ Phloem: The system transporting products of photosynthesis from the leaves where they are synthesized to other parts of the plant is called phloem.

→ Translocation: The transport of soluble products of photosynthesis is called translocation and it occurs through the phloem.

→ Artery: The blood vessels which carry the oxygenated blood from the heart to various parts of the body are called arteries.

→ Veins: The blood vessels which bring the deoxygenated blood from various parts of the body to the heart are called veins.

→ Capillaries: Very thin blood vessels within the tissues which connect arteries with veins.

→ Lymph: It is a clear-to-white fluid containing white blood cells that attack bacteria in the blood.

→ Hemoglobin: The iron-containing red pigment present in red blood cells to transport oxygen is called hemoglobin.

→ Clotting: The process of blood clot formation in the body is called clotting.

→ Dialysis: It is a process of removing waste and excess water from the blood and is used as an artificial replacement for kidney failure.

→ Osmoregulation: The process of maintaining a balance of water and ions inside the body is called osmoregulation.

→ Excretion: Excretion is the process by which waste products of metabolism are eliminated from the body.

→ Nephron: The basic functional unit of the kidney is called a nephron.

This PSEB 10th Class Science Notes Chapter 5 Periodic Classification of Elements will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 5 Periodic Classification of Elements

→ The arrangement of elements in such a manner that the elements having similar elements are grouped together whereas the elements having different properties are separated is called classification of elements.

→ According to Dobereiner Triads, the elements were arranged in order of increasing atomic masses and grouped into three elements such, that the elements had similar properties such that the atomic mass of the middle element was average of the other two elements.

→ The classification done by Dobereiner on the basis of triads was not applicable to classify all the elements.

→ In 1866, on the basis of the law of octaves, Newland classified elements till calcium whose atomic mass is 40.

→ Russian chemist, Mendeleev discovered periodic law which is famous by the name Mendeleev’s periodic law which states that the physical and chemical properties of the elements are the periodic functions of their atomic masses.

→ Mendeleev’s periodic table was arranged into periods and groups.

→ Horizontal rows are called periods and vertical columns are called groups.

→ In the main periodic table, Mendeleev left the places for those elements which were not discovered till then.

→ According to Modern Periodic Law, the physical and chemical properties of elements are the periodic functions of their atomic number.

→ In modern periodic tables, elements are arranged in 18 vertical columns known as groups and 7 horizontal rows known as periods.

→ Elements of group zero/18 are known as noble gases.

→ The repetition of the similar properties of elements placed in a group and separated by definite gaps of atomic number is called periodicity.

→ There are also some defects in the long form of the periodic table.

→ Scandium, gallium, germanium, etc., were discovered after Mendeleev’s periodic table. In 1913, Henry Moseley said that in comparison to the atomic mass of elements, atomic number is a more fundamental property.

→ By arranging the elements in ascending order of atomic number, their properties can be estimated more precisely.

→ By atomic size, we can find the atomic radius.

→ The atomic radius of Hydrogen is 37 pm (Picometer, 1 pm = HP12 m).

→ Atomic radius decreases on moving left to right along a period.

→ By metalloids properties of metal and non-metals are differentiated. Metalloids are-Boron, Silicon, Germanium,

→ Arsenic, Antimony, Tellurium, and Polonium. Oxides of metals are basic and oxides of non-metals are acidic.

→ The minimum energy required to remove an electron from the valence shell of an isolated gaseous atom is known as ionization energy.

→ The energy released when an electron enters the outermost shell of a neutral gaseous atom is known as electron affinity.

→ As we move down in a group, metallic properties increases.

→ On moving down in a group from top to bottom ionization energy decreases.

→ Periodic Table: This is a table in which we classify the elements in a specific order.

→ Newlands’ Law of Octaves: It states that when the elements are arranged in the ascending order of their increasing atomic weights, every eighth element has properties similar to the first element like the notes of an octave of music.

→ Dobereiner’s triads: It is a group of three elements having similar chemical properties in which the atomic weight of the middle element is the average of the other two elements.

→ Periodic classification is the systematic study of the properties of the elements.

→ Periodic Table: It is a table or chart in which the various elements are arranged in such a manner that elements having similar properties fall in the same vertical column whereas dissimilar elements are separated.

→ Mendeleev’s Periodic Table: The table of elements made by Mendeleev is known as Mendeleev’s Periodic Table, which is based on atomic mass.

→ Modern Periodic Table: The table which was made after the modification of Mendeleev’s Periodic Table, is known as Modern Periodic Table or extended form of the periodic table. It is based on atomic number.

→ Mendeleev’s Periodic Law: Physical and chemical properties of elements are the periodic functions of their atomic masses.

→ Periods: Horizontal rows in a periodic table are known as periods.

→ Groups: Vertical columns of the periodic table are known as groups.

→ Modern Periodic Law: The physical and chemical properties of elements are the periodic function of their atomic number.

→ Periodicity: Repetition of characteristics of elements in a group is known as periodicity.

→ Atomic Radius: The distance from the nucleus of an atom to its outer shell is known as atomic radius.

→ Valence Electrons: The number of electrons in the valence shell of an atom is known as valence electrons.

→ Ionization Potential: The ionization potential of an element is the minimum energy required to separate an electron from the outermost shell of a gaseous atom of that element.

→ Electron Affinity: The energy released when an electron enters the outermost shell of a neutral gaseous atom is known as electron affinity.

→ Valency is the combining capacity of the element and is equal to either the number of valence electrons or eight minus the number of valence electrons.

→ Lanthanides: Fourteen elements starting from lanthanum having atomic numbers 58 to 71 are called lanthanides.

→ Actinides: Fourteen elements starting from actinium having atomic numbers 90 to 103 are called actinides.

→ Metalloids: Elements that behave both as metals and non-metals are called metalloids.

→ Periodic Properties: These are the properties of an element that are related to the electronic configuration of its atom and change periodically down a group and along a period.

→ Atomic Size: In a period, with the increase of atomic number, there is a decrease in atomic radius. By going from left to right, the atomic number increases, and the size of the atom decreases. This is called atomic size.

→ Representative Elements: The elements of sub-group A are known as representative elements.

→ Need for classification: Elements are grouped based upon similarities in their properties in order to simply and systematically study of the properties of the elements.

Modern Periodic Table:

This PSEB 10th Class Science Notes Chapter 4 Carbon and its Compounds will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 4 Carbon and its Compounds

→ In our daily life, the maximum things used by us are compounds of carbon.

→ All living species involve carbon.

→ A very small quantity of carbon present in nature is used by us.

→ Most of the carbon compounds are not good conductors of electricity.

→ The bonding of carbon compounds does not produce any ions.

→ The atomic number of carbon is 6. It has four electrons in its outermost shell.

→ It can gain four electrons forming C^4- anion or it can lose four electrons forming C⁴⁺ cation.

→ Hydrogen requires one or more than one electron. The shared pair of electrons is said to constitute a single bond between two hydrogen atoms.

→ Chlorine forms a diatomic molecule.

→ Oxygen forms a double bond between two oxygen atoms.

→ In order to attain an octet, each nitrogen atom in a molecule of nitrogen contributes three electrons giving rise to three shared pairs of electrons.

→ Methane is a compound of carbon. It is the major component of bio-gas and compressed natural gas (CNG).

→ It is one of the simplest compounds of carbon.

→ Diamond and graphite are allotropes of carbon. They have the same chemical properties.

→ Fullerenes form another class of carbon allotropes which was first identified as C-60.

→ There are around 3 million carbon compounds in number.

→ The nature of a covalent bond enables carbon to form a very large number of compounds.

→ Carbon shows Catenation to the maximum extent.

→ The organic compounds having the presence of carbon-carbon single bonds only are termed saturated compounds.

→ The carbon-Carbon bond is very stable and strong.

→ Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine, and some other elements.

→ Since carbon has a valency of four and is capable of bonding, it forms a large number of compounds.

→ The saturated compounds of carbon and hydrogen are methane, ethane, propane, butane, pentane, hexane.

→ The compounds with identical molecular formulas but different structures are called structural compounds.

→ In addition to straight and branched carbon chains, some compounds have carbon atoms arranged in the form of rings. For example, cyclohexane.

→ Saturated hydrocarbons are called ‘Alkanes’. Such unsaturated hydrocarbons which have one double bond are called ‘Alkenes’. Those having one triple bond are called Alkynes’.

→ All hydrocarbons burn in the presence of oxygen and release heat, light, and CO₂.

→ Saturated hydrocarbons generally produce clean flame on burning while unsaturated carbon compounds produce a yellow flame with a lot of black smoke.

→ Incomplete combustion produces a sooty flame.

→ A flame is produced when gaseous substances are burnt.

→ Coal and petroleum are fossil fuels that have been formed from biomass that has been subjected to various biological and geological processes.

→ Alcohol can be converted into carboxylic acids by complete oxidation.

→ Substances that are capable of adding oxygen to other substances are known as oxidizing agents.

→ Catalysts are substances that cause a reaction to occur or accelerate the rate without reacting and getting affected.

→ Ethanol is a liquid at room temperature. Ethanol is commonly called alcohol.

→ Consumption of small quantities of ethanol tends to slow metabolic processes and depress the central nervous system.

→ Consumption of methanol even in very small quantity can cause death. It can also cause blindness by affecting the optic nerve.

→ Methanol is mixed with ethanol to prevent its misuse. Dyes are added to colour the alcohol blue. This is called denatured alcohol.

→ Sugarcane juice can be used to prepare molasses which is fermented to give ethanol.

→ Ethnic acid is commonly called acetic acid. 3.4% solution of acetic acid in water is called vinegar.

→ Carbon: Carbon is an element that is of immense significance in its elemental and combined form. Placed in 14th group of periodic table with atomic number 6, mass number 12 and electronic configuration 4 it has electronic valency 2, 4 and is symbolised as \({ }_{6}^{12} \mathrm{C}\).

→ Carbon compounds: The compounds in which carbon is present are called carbon compounds. These are generally covalent. Ionic compounds of carbonates are not included in this.

→ Covalent bonds: The bond formed by sharing of electrons is known as a covalent bond.

→ Allotropy: The property of an element by virtue of which it can exist in two or more physical forms of the same chemical element, with the same chemical properties.

→ Hydrocarbons: The covalent compounds of hydrogen and carbon are called hydrocarbons.

→ Saturated hydrocarbons: The hydrocarbons with the same chemical formula C_nH_2n+2 are called alkane. These have a covalent bond between the members of the same category.

→ Isomerism: The compounds with the same molecular formula but different structural formulas are called isomers and the phenomenon is known as isomerism.

→ Unsaturated Hydrocarbons: The compounds of carbon having double or triple bonds between the carbon atoms are known as unsaturated hydrocarbons.

→ Alkene: Generally a hydrocarbon with the chemical formula C_nH_2n is called alkene.

→ Alkyne: The carbon compound containing a triple bond between carbon atoms is called alkyne.

→ Catenation: The carbon atoms form bonds with other carbon atoms to form long-chained compounds. This property is known as catenation.

→ Allotropy: The phenomenon of the existence of two or more physical forms of the same chemical element, with the same chemical properties, is called allotropy.

→ Fullerenes: There are the allotropes of carbon having a football or bucky ball-like structure.

→ Addition reactions: These are the reactions in which some molecules get added to unsaturated Hydrocarbon like alkene/alkyne.

→ Substitution reactions: These are the reactions in which an atom or group of atoms from an organic compound is replaced by another atom or group.

→ Esterification: The reaction of a carboxylic acid with an alcohol to form an ester is called esterification.

→ Functional group: An atom or group of atoms that determines the chemical properties of an organic compound is called a functional group.

→ Fermentation: The process of conversion of complex organic compounds into simple organic compounds with the help of enzymes is known as fermentation.

→ Alcohol: The compound obtained by the replacement of a hydrogen atom of alkane by hydroxyl (-OH) functional group is called alcohol: Its general formula is C_nH_2n+1 OH.

→ Carboxylic acid: Carboxylic acids are those organic compounds that have (-COOH) as a functional group.

→ Homologous series: A series of organic compounds having the same functional group formula and possessing similar chemical properties are termed homologous series.

This PSEB 10th Class Science Notes Chapter 3 Metals and Non-metals will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 3 Metals and Non-metals

→ Iron, Copper, Aluminium, Magnesium, Sodium, Lead, Zinc, etc. Metals are easily available.

→ Metals have shining surfaces, called metallic luster.

→ Sodium metal can be cut by a knife.

→ Metals are usually hard and can be beaten into thin sheets and drawn into wires.

→ Gold is most ductile that is why from one gram of gold, a 2km long wire can be drawn.

→ Metals are good conductors of heat.

→ Malleability and ductility are two important properties of metals.

→ Lead and mercury are bad conductors whereas silver and copper are very good conductors.

→ Metals have sonorous properties.

→ Carbon, Sulphur, Iodine, Oxygen, Hydrogen etc. are non-metals.

→ Bromine is a non-metal which exists in liquid form.

→ Mercury exists in liquid form at room temperature.

→ Gallium and Cesium have a very low melting point, which melts even when placed on our palms.

→ Iodine is non-metal but is lustrous.

→ Lithium, Sodium, Potassium are alkali metals and are very soft, they can be cut with a knife.

→ Most of the non-metals produce acidic oxides when dissolved in water.

→ Magnesium burns in the air with dazzling white flame.

→ On heating copper, it changes to black coloured copper oxide.

→ Those metal oxides that react with acid as well as with bases and produce salt and water in both cases are called amphoteric oxides.

→ Gold and silver do not react with oxygen even on heating.

→ Aqua regia is a fresh mixture of concentrated HCl and Concentrated HNO3 in the ratio 3 : 1.

→ Aqua regia can dissolve in Gold and platinum.

→ Reactivity series is a list of metals in which metals are arranged in decreasing activity.

→ Noble gases have completely filled valence shells and thus are less reactive.

→ Helium, Neon, Argon are Noble gases.

→ Compounds formed by the transfer of electrons from metals to non-metals are called ionic or electrovalent compounds.

→ Ionic compounds are solid and hard. They have high melting and boiling point. They can conduct electricity.

→ Earth’s crust is the main source of metals.

→ The elements or compounds which occur naturally in the earth’s crust are called minerals.

→ Some of the minerals from which extraction of metals is easy and profitable are called ores.

→ Gold, silver, platinum, and copper are at the bottom of the reactivity series and are least reactive, and are found in a free state.

→ Zinc, Iron, lead are moderately reactive and are found in the form of oxide, sulphide, or carbonate in the Earth’s crust.

→ Sodium, Potassium, calcium, Magnesium, Aluminium, etc. are at the top of the reactivity series and are so reactive that they are never found in a free state in nature.

→ Ores are contaminated with impurities like soil, sand, etc. known as gangue.

→ If sulphide ores are heated in excess air, they convert to oxides. This is called roasting.

→ Carbonate ores are converted into oxides by heating them strongly in a limited supply of air. This is known as calcination.

→ The reaction of iron oxide with aluminium is called the thermit reaction.

→ Electrolytic refining is used to purify metals.

→ Silver articles become black after some time when exposed to air due to the formation of a coating of silver sulphide.

→ Copper gains a green coating of basic copper carbonate due to corrosion when left in air for a long time CuCO₃.Cu(OH)₂.

→ Iron acquires a brown coating called rust.

→ Corrosion is prevented by greasing, painting, galvanising, chrome plating, anodizing, etc.

→ The homogeneous mixture of two or more two metals is called an alloy.

→ Pure Gold, which is 24-carat gold, which is very soft.

→ For making ornaments silver or copper is mixed with gold.

→ Generally, 22-carat gold is used for making ornaments. If alloy contains one of its constituents as mercury (Hg) it is called amalgam.

→ Alloy Bronze is a bad conductor of electricity.

→ Ductility: It is a property of metals by virtue of which long wires can be drawn. Electric wire is an example of ductility.

→ Malleability: It is a property of metals by virtue of which metals can be beaten into thin sheets.

→ Conductivity: Metals allow the passage of heat and electricity through them, this is called conductivity.

→ Mineral: Substances from which metals can be extracted are called minerals. Metals can be extracted from minerals by different methods.

→ Metallurgy: To extract metals from their ores and purify them for use is called metallurgy.

→ Ore: Those minerals from which metal extraction is easy and profitable are called ores.

→ Gangue: Ores mined from the earth are contaminated with impurities such as soil, sand, etc. are called gangue.

→ Roasting: The process of converting enriched ore in the excess of air is called roasting.

→ Reduction: It is a process of obtaining metals from compounds.

→ Purification: It is a process of obtaining pure metal from impure metal.

→ Alloy: Mixture of a metal with other metal or non-metal in the called alloy.

→ Allotropy: A property by virtue of which non-metals exist in different forms is called allotropy.

→ Vulcanization: Mixing sulphur with natural rubber is called vulcanization and such rubber is called vulcanized rubber.

→ Slag: It is a substance that is obtained when gangue and smelter are together.

→ Smelter: It is a substance which is used to separate gangue in the form of liquid from an impure metal.

→ Calcination: It is a process of heating ore in the limited supply of air. Ore becomes porous in this process.

→ Smelting: It is a process to extract an element from its ore using heat and a reduction agent.

→ Metals: Metals are those elements which lose electrons to form positive ions.

→ Non-Metals: Non-Metals are those elements which gain electrons to form negative ions.

→ Amalgam: When one of the constituents of an alloy is mercury it is called an alloy.

→ Corrosion: The effect of air, water, or any other substance on the surface of the metal is called corrosion.

→ Strategic metals: These are the metals that are important for the economy and safety of the country are strategic metals.

→ Electropositive elements: Those elements which lose electrons to form positive ions are known as electropositive elements: Metals belong to this category.

→ Electronegative elements: Those elements which gain electrons to form negative ions are known as electronegative elements. Non-metals belong to this category.

→ Reactivity series of metals: Arrangement of metals in a column in decreasing reactivity of metals is called reactivity series of metals.

→ Displacement reactions: The replacement of less reactive metal by more reactive metal from its salt in a reaction is called displacement reaction.

→ Catalyst: These are substances that do not take part in a reaction but can increase or decrease the rate of reaction are called catalysts.

→ Promotor: Substances that increase the performance of catalysts are called promotors.

This PSEB 10th Class Science Notes Chapter 2 Acids, Bases and Salts will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 2 Acids, Bases and Salts

→ The sour taste of foods is due to acids and the bitter taste is due to bases present in them. Acids turn blue litmus into red and bases turn the red litmus into the blue.

→ Acids and bases neutralize each other’s effects.

→ Acids and bases can be tested using litmus, turmeric, methyl orange, and phenolphthalein indicators.

→ On passing carbon dioxide gas through lime water, lime water turns milky.

→ On passing, excess carbon dioxide gas through lime water, its milky colour disappears due to the formation of soluble calcium bicarbonate.

→ Bases turn phenolphthalein pink in colour.

→ Acids and bases react to produce salt and water.

→ The flow of current in the solution is due to ions present in the solution.

→ In acids H+ ions are present. Acids produce hydrogen ion H⁺(aq) in a solution due to which solutions become acidic.

→ Bases produce hydroxide (OH^–) ions in water.

→ Alkali is a base that dissolves in water.

→ Bases are soapy to touch, bitter, and corrosive.

→ All acids produce H⁺(aq) and bases produce OH^–(aq) in an aqueous solution.

→ The process of the dissolving of acids or bases in water is highly exothermic, therefore to dilute them these should be added and mixed slowly in water. Never add water to concentrated acid.

→ A universal indicator is a mixture of several indicators.

→ Universal indicators show different colors for different concentrations of hydrogen ions in the solution.

→ A scale known as the pH scale has been developed for measuring the concentration of hydrogen ions present in the solution.

→ The ‘p’ in pH stands for ‘potenz’ this is a German word which means power.

→ On the pH scale, we can measure pH generally from 0 (very acidic) to 14 (very basic).

→ Higher is the concentration of hydronium ion, less is the value of pH. A neutral solution has a pH value of 7.

→ If the value of pH is less than 7 then the solution is acidic and if pH lies between 7 to 14 then the solution is basic.

→ Those acids which produce a large number of H⁺ ions are called strong acids and those acids which produce less H⁺ ions are weak acids.

→ Our body works in the range of 7.0 to 7.8.

→ When the pH value of rainwater is less than 5.6 it is called acid rain.

→ To get rid of acidity in the body, and antiacid like magnesium hydroxide which is a weak base is used.

→ If the pH value is less than 5.5 in the mouth, decay of teeth starts.

→ Nettle is a herbaceous plant that causes painful stings due to methanoic acid present in stinging hair. A traditional remedy is rubbing the area with the leaf of the dock plant.

→ Common salt (NaCl) is produced by the reaction between hydrochloric acid and sodium hydroxide.

→ Bleaching powder is produced by the action of chlorine on dry slaked lime.

→ Bleaching powder is used in the paper and textile industry for bleaching. It acts as an oxidant and as a disinfectant.

→ Baking soda (NaHCO₃) is produced from sodium chloride.

→ Sodium hydrogen carbonate is a mild non-corrosive base. It is used in the production of Baking powder and used in the preparation of cakes. It is also used in fire extinguishers.

→ Washing soda (NagCO₃.10H₂O) is prepared from sodium chloride. It is used in the glass, soap, paper industries. It is used to remove the permanent hardness of the water.

→ The chemical formula for hydrated copper sulfate is CuSO₄.5H₂O and of gypsum is CaSO₄.2H₂O.

→ Plaster of Paris is obtained from calcium sulphate hemihydrate (CaSO₄. \(\frac{1}{2}\) H₂O) by heating it at 373K.

→ Plaster of Paris is used for making toys and material for decoration.

→ Indicators: These are the substances that give different colors in acidic and basic solutions e.g. litmus, turmeric, phenolphthalein, methyl orange, etc.

→ Olfactory Indicators: There are some substances whose odour changes in acidic or basic media, which are known as olfactory indicators.

→ Acid: Those compounds which have one or more hydrogen atoms and which give hydrogen (H⁺) or hydronium (H₃O⁺) ions (H₃O⁺) ion in an aqueous solution are called acids. These are sour in taste.

→ Ionization: It is a process in which a substance produces ions in water, ionization.

→ Basicity of an acid: Basicity of an acid is the number of hydronium ions [H⁺] produced when one molecule of acid gets completely ionized in an aqueous solution.

→ Base: Bases are those compounds which are metal oxides or metal hydroxide or aqueous ammonia and these react with hydronium ion (H₃O⁺) of acids to produce salt and water.

→ Neutralization: Due to the reaction between acids and bases, salt and water are produced. This is called a neutralization reaction.

→ Alkali: Those basic hydroxides which on dissolving in water form hydroxyl (OH^–) ions, are called alkali.

→ Universal indicator: It is a mixture of various organic substances which show different colours with solutions having different pH values.

→ Dissociation: When a molecule or ionic compound dissociates into two or more atoms or ions, this is called dissociation.

→ Chemical dissociation: A reaction in which a molecule of a compound breaks into atoms or ions is called chemical dissociation.

→ The water of Crystallisation: Water, which is present in crystals of a substance is called water of crystallization. e.g., FeSO₄.7H₂O, Al₂O₃.2H₂O, CuSO₄.5H₂O, Na₂CO₃.10H₂O.

→ Efflorescence: The process of release of crystalline water from hydrated salts into the air is called efflorescence.

→ Deliquescence: This is a process in which a substance absorbs moisture from the atmosphere and dissolves in the absorbed water to form a solution.

→ Dilution: On mixing acid or base in water, the concentration of ions (H₃O⁺/OH^–) per unit volume becomes less. This is called dilution.

→ Chlor-alkali process: The electrolysis of sodium chloride solution is called chlor-alkali process.

This PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 1 Chemical Reactions and Equations

→ In a chemical reaction, old bonds in the reactants are broken forming new bonds to give products.

→ A chemical equation represents a chemical reaction.

→ By using chemical formulae instead of words, chemical equations can be made more useful and concise.

→ According to the law of conservation of mass matter (or Mass) can neither be created nor destroyed in a chemical reaction.

→ If the number of atoms of each element is the same on both sides of the arrow in a chemical reaction then the chemical equation is a balanced equation.

→ The method used to balance chemical equations is known as the Hit-and-Trial method since we make trials to balance the equation by using the smallest whole number coefficient.

→ The solid, gas, liquid, and aqueous states of reactants and products are represented by the notations: (s), (g), (l), and (aq) respectively.

→ When reactants and products are present as solutions in water then the word aqueous (aq) is written.

→ When (g) is written with water, it means that water is present in the form of vapour.

→ A reaction in which two or more reactants combine to form a single product is known as a combination reaction.

→ The chemical formula for marble is CaCO₃.

→ After two three days of whitewashing, calcium carbonate is formed which gives a shiny finish to the walls.

→ We get energy from food.

→ During digestion, food is broken into fine particles of simpler substances.

→ The decomposition of vegetable matter into compost is an example of an exothermic reaction.

→ A reaction in which a single reactant breaks down to give simpler products is called a decomposition reaction.

→ On heating, crystals of ferrous sulfate crystals lose water, and their color changes.

→ NO₂ fumes are brown in colour.

→ The white colour of silver chloride changes into a grey colour in sunlight.

→ The chemical reactions in which energy is given out are called exothermic reactions.

→ Those reactions in which energy is absorbed are known as endothermic reactions.

→ Those reactions in which there is an exchange of ions between the reactants are called double displacement reactions.

→ Those reactions in which precipitates are formed are known as precipitate reactions.

→ If in a reaction one of the reactants gets oxidized and the other gets reduced, then such a reaction is called a redox reaction.

→ In a reaction, a substance is oxidized when there is a gain of O₂ or a loss of H₂ in it.

→ A substance is reduced when it gains H₂ or loses O₂.

→ When a metal comes in contact with acid or moisture around it, gets corroded and the process is called corrosion.

→ Examples of corrosion are black coating on silver and green coating on copper.

→ Oxidation of oils and fats become rancid and their taste and smell change.

→ To slow down the oxidation process of food materials these are kept in air-tight containers.

→ Chemical change: It is a reaction in which new substances are formed. It is called a chemical change.

→ Chemical reaction: A process in which chemical change takes place is called a chemical reaction.

→ Reactants: Those substances which take part in a chemical reaction are called reactants.

→ Products: Those substances which are formed in a chemical reaction are called products.

→ Combination reaction: It is a chemical reaction in which two or more two substances combine to form a single substance.

→ Decomposition reaction: It is a chemical reaction in which a molecule breaks into molecules of simpler substances.

→ Displacement reaction: A reaction in which a substance displaces another substance is called a displacement reaction.

→ Double displacement reaction: This is a reaction in which there is a mutual exchange between two different atoms or groups of atoms.

→ Neutral solution: When an acid and a base are mixed in a proper proportion, then we get a neutral solution.

→ Neutralisation reaction: When we get salt and water as the only products by mixing acid and base, then such a reaction is known as a Neutral reaction.

→ Oxidation: A substance is oxidized when there is a gain of oxygen or a loss of hydrogen in the substance.

→ Reduction: A substance is reduced when there is a loss of oxygen and a gain of hydrogen in the substance.

→ Redox reaction: A reaction in which oxidation and reduction both take place simultaneously is called a redox reaction.

→ Exothermic reaction: Those reactions in which heat is produced along with the products are called exothermic reactions.

→ Endothermic reactions: Those reactions in which heat is absorbed are called endothermic reactions.

→ Precipitation reactions: When two solutions are mixed and due to reaction between them a white coloured substance (or some other colour) is formed which is insoluble in water, then this is called a precipitation reaction.

→ Fermentation: The change of carbonic substances with the help of microorganisms or enzymes into simple carbonic substances is called fermentation.

→ Rancidity: When fat/oil-containing food materials are left for a long time then due to oxidation there is a change in their smell and taste, this change is called rancidity.

→ Reducing agent: That substance that gets oxidised itself or reduces the other substances by giving electrons is called a reducing agent.

→ Oxidizing agent: That substance that gets reduced itself or oxidizes the other substances by gaining electrons is called an oxidizing agent.