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Nutrition is of two types. 

1) Autotrophic nutrition and 

2) Heterotrophic nutrition

(a) Solid state: Ice, glass, rock, most metals, table sugar, frozen CO₂ (dry ice), wood, butter etc. 

(b) Liquid state: Water, alcohol, milk, mercury, vegetable oil, ethanol, bromine, blood, honey, coffee etc. 

(c) Gaseous state: Air, helium, nitrogen, water vapour, propane, natural gas, ozone, hydrogen sulphide etc.

C) Ammonium chloride

C) higher speed, greater space

C) R₁ and R₂ 

The process of intake and utilization of food by organisms is called nutrition. This is mainly of two types.

1. Autotrophic nutrition

2. Heterotrophic nutrition

1) Autotrophic nutrition : 

The mode of nutrition in which organisms make food by themselves is called autotrophic nutrition. 

Ex: 

Green plants 

2) Heterotrophic nutrition : 

The mode of nutrition in which organisms depend on other organisms for food is called Heterotrophic nutrition. 

This is again of three types 

i) Saprophytic nutrition: 

The mode of nutrition in which organisms take in nutrients in the form of solution from dead and decaying matter is called saprophyticnutrition. 

Ex:

 Certain microorganisms such as bacteria and fungi like mushrooms, bread mould etc. 

ii) Parasitic Nutrition : 

This type of association between two organisms for food in which one organism get benefited and other is vitiated is called parasitic nutrition. 

Ex: 

Cuscuta, Intestinal worms 

iii) Holozoic Nutrition : 

Holozoic Nutrition is the mode of heterotrophic nutrition in which the food is taken in solid or liquid form from the outside and is digested inside the body. 

Ex: 

Amoeba. Human beings

Sublimation: Some substances may change from solid to a gaseous state and vice versa without passing through the liquid state. This is called sublimation. Ex: Iodine, Camphor, etc.

(1) Take one meter long narrow glass tube. 

(2) Take two pieces of cotton wool. 

(3) Soak one piece in yhydrochloric acid (HCl) Solution and another in ammonia (NH₃) solution. 

(4) Insert them separately at the two ends of the tube. Block the ends of the tube and observe. 

(5) The hydrochloric acid (HCl) gives off (hydrogen chloride (HCl) and ammonia solution (NH₃) gives off ammonia gas (NH₃). 

(6) Both gases react together to form a white fumes called ammonium chloride (NH4Cl) (White ring). 

(7) The ring usually forms nearer to the HCl acid end of the tube because HCl diffuses more slowly than ammonia (NH₃). 

(8) Thus we can prove the speed of diffusion of NH₃ is more than that of the speed of diffusion of HCl acid.

1. artificial, polymer
2. artificial silk
3. Orion
4. synthesised polymer

The rate of diffusion in gases is very high than liquids and gases, because

1. Higher speed of gas particles. 

2. Greater space between the particles of gas.

(1) Solids have definite mass, shape and volume. 

(2) They have least kinetic energy of particles. 

(3) Compressibility and fluidity is not possible. 

(4) They have heigh density and inter particle forces. 

(5) They diffuse very slowly. 

(6) Expansion on heating is very less. 

(7) They have oscillatory motion of constituent particles.

(8) They are high rigid.

(1) Liquids acquire the shape of the container. 

(2) They have definite volume. 

(3) Almost negligible compressibility. 

(4) Less rigid. 

(5) They diffuse fastly. 

(6) Packing of particles is less. 

(7) Inter particle forces slightly weaker than in solids. 

(8) Expansion on heating is more than solids.

When a substance is heated its state changes from solid to vapour directly without changing into liquid. This is called sublimation.

(1) Gases acquire the shape of the container. 

(2) They have indefinite volume. 

(3) They are highly compressible. 

(4) The diffuse very fast. 

(5) Interparticle forces is negligible.

(6) They are least closely packed. 

(7) They are not rigid. 

(8) Fluidity is more.

1. Ask your friend to hold an unlit incense stick and stand in one corner of the room. 

2. Then you go and stand in the other corner. 

3. We cannot observe any smell (This depends on the type of incense stick). 

4. Now ask your friend to light the incense stick. 

5. After a few seconds, we can observe the smell of incense stick. 

6. The scent in the vapour form and smoke mixes with air and moves across the room and reaches our nose. 

7. This activity proves that the gases can diffuse.

(1) Gas cylinders - gas is compressed and stored in cylinders. 

(2) Shaving cream is compressed, so it comes outside as a foam. 

(3) Due to the compressibility only medicines in syringe infected in to our body through needle. 

(4) Due to the compressibility property only liquids adjust themselves in a container

1. Brush teeth twice a day with fluoride tooth paste. 

2. Use dental floss to clean between your teeth. 

3. Change your tooth brush every 3 months. 

4. Cut down on how often you have sugary foods like chocolates, sweets and cool drinks. Visit dentist regularly.

The above habits should practise for healthy teeth. Because, if we do not clean our teeth and mouth after eating, many harmful bacteria begin to live and grow in mouth. These bacteria breakdown the sugars present from left over food and release acids. These acids gradually damage teeth and causes severe toothache.

(1) The mixing of different gases in air is a natural process that takes place continuously. 

(2) Smoke coming out of factories is seen only near the mouth of chimneys. After rising high it mixes up with air and vanishes out. This happens becaues of diffusion or gases. 

(3) When salt solution kept in water this makes the whole solution salty after some times. This happens because of diffusion in liquids. 

(4) Alloys are possible to get prepared because of the diffusion of solid into solid. Bronze steel, brass are examples of alloy

(1) A tea bag placed in a cup of hot water will diffuse into the water. 

(2) Cigarette smoke diffuses into the air. 

(3) In leaves, oxygen from the leaf cells diffuses out to the air. 

(4) In leaves CO₂ diffuses from the air spaces between mesophyll cells to the chloroplast.

The gases like oxygen and carbon dioxide will diffuse in water. The acquatic animals under water will survive by inhaling these gases.

Plastic is a polymer like a synthetic fibre. The arrangement of units in a plastic can be linear or cross-linked. Plastic articles are available in all possible shapes and sizes. It can be easily moldable and can be shaped in any form. It can be recycled, reused, coloured, melted and can be rolled into sheets or made into wires. Plastic is used to manufacture toys, combs, containers, utensils and electrical switches.

Nylon is the first fully synthetic fibre. Nylon is the first fully synthetic fibre. 

Following are the uses of nylon:

• It is highly durable and is used for making seatbelts and tire cords. 

• Nylon fibres is very strong, elastic and light. It is lustrous and easy to wash. Hence, it became very popular for making clothes. 

• A nylon thread is actually very strong than steel wire. It is also used for making parachutes and ropes for rock climbing. 

• It is also used for making articles such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags and curtains.

(a) man-made or artificial, Rayon and nylon are the examples of synthetic fibers. 

(b) petrochemicals, Nylon was the first fully synthetic fiber. It was petrochemicals which is derived from fossil fuels 

(c) polymer , The arrangement of units in a plastic can be linear or cross-linked. 

(d) paper or jute bag Disposal of plastic is a major problem. This is can be reduced by use paper or jute bag.

The materials which gets decomposed through natural processes, such as by the action of microorganisms are called biodegradable materials. 

For example, peels of vegetables and fruits, cotton clothes, wood and paper are biodegradable substances. These materials are easily decomposed by microorganisms. Temperature and sunlight may also play roles in the decomposition of biodegradable plastics and other materials.

The materials which are not easily decomposed by natural processes are called non biodegradable materials. 

For example, tin, aluminium and other metal cans and plastics are non-biodegradable materials. Plastics can take several years to decompose. These materials are not environmental friendly and cause environmental pollution.

1. Diffusion is a very important process for living things. 

2. Oxygen diffuses into air and available for every human beings and animals. 

3. CO diffuses into air and available to plants. 

4. Oxygen and CO diffuse and disolve in water and support the survival of aquatic animals and plants. 

5. During respiration oxygen diffuses from lungs into blood. 

6. Smell of flowers, scents diffuses and reaches to our nose to give happiness to us. 

7. We can recognise leaking of L.P. Gas in our house by diffusion process. 

8. Diffusion of sugar and salt, give taste to drinks.

9. In this way diffusion is useful in our daily life. So, I am appreciating the process of diffusion.

1. It is clear that solids and liquids diffuses into liquids and gases diffuses into gases. 

2. Certain gases from atmosphere particularly oxygen and carbon dioxide diffuse and dissolve in water and support the survival of aquatic animals and plants. 

3. Diffusion therefore is a very important process for living things. 

4. During respiration oxygen diffuses from lungs into blood. Carbon dioxide diffuses from blood into lungs.

A synthetic fibre is made of small units which are joined together. These units are made of chemical substances. Such small units combine to form a large single unit called a polymer. Hence, a polymer is made of many repeating units. Polymers also occur in nature. For example, cotton is a natural polymer which is made from the cellulose. Cellulose is made up of a large number of glucose units.

Viscous force acting between two layers of liquids depends on, 

1. area of the layers 

2. relative velocity of the two layers and 

3. distance between two layers.

Nylon is the first fully synthetic fibre. It was made in 1931, without the use of any natural raw material from plants or animals. It was prepared from coal, water and air. 

Following are the properties of nylon:

• Nylon has the ability to show variation of luster. It has the ability to be very lustrous, semi lustrous or dull. 

• It is highly durable and is used for making seatbelts and tire cords. 

• Nylon fibre is very strong, elastic and light. It is lustrous and easy to wash. Hence, it became very popular for making clothes. 

• A nylon thread is actually very strong than steel wire. It is also used for making parachutes and ropes for rock climbing. 

• It is also used for making articles such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags and curtains.

Plastic is a polymer like a synthetic fibre. The arrangement of units in a plastic can be linear or cross-linked. 

Based on the arrangement of monomers, plastics are of the following types:

• Thermoplastics: The plastics which gets deformed easily on heating and can be bent easily are called thermoplastics. For example, polythene and PVC are thermoplastics. These are used in the manufacturing of toys, combs and different types of containers. 

• Thermosetting plastics: The plastics which when moulded once, cannot be softened by heating are called thermosetting plastics. For example, Bakelite is a thermosetting plastic which is a poor conductor of heat and electricity. It is used to make electrical switches and handles of utensils. Melamine is a thermosetting plastic which is resistant to fire and can tolerate heat better than other plastics. It is used to make floor tiles, kitchenware and fire resistant fabrics.

Rayon can be used in the following ways: 

• It can be mixed with cotton to make bed sheets. 

• It can also be mixed with wool to make carpets. 

• It is also used in textile industry to make textiles.

C) Long glass tube, cotton, HCl, NH₃ 

A synthetic fibre is made of small units which are joined together. These units are made of chemical substances. Such small units combine to form a large single unit called a polymer. Hence, a polymer is made of many repeating units. 

Following are the characteristics of synthetic fibres:

• Synthetic fibres absorb very less water and they dry up quickly. 

• They are durable and are less expensive. 

• They are readily available and are easy to maintain. 

• Due to such unique properties, synthetic fibres are used to make dress materials.

Synthetic fibres are man-made fibres which are made up of small units which are joined together. These units are made of chemical substances. Such small units combine to form a large single unit called a polymer. Hence, a polymer is made of many repeating units. Polymers also occur in nature.

Example: Rayon and Nylon are synthetic fibres. Rayon is obtained by the chemical treatment of wood pulp or cellulose. Nylon is the first fully synthetic fibre. It was prepared from coal, water and air.

B) water, test tube, China dish

Evaporation of iodine, drying up of wet body, etc.

Rayon is the man-made fibre prepared from the natural materials. It is the man-made fibre which is regarded as artificial silk. It is obtained by the chemical treatment of wood pulp or cellulose. Although rayon is obtained from natural source, wood pulp, yet it is a manmade fibre. Its fibres can also be woven like those of natural fibres. It is cheaper than silk but can be woven like silk fibres. It can also be dyed in a variety of colours.

1 decapoise = 10 poise

Mass/length = [M¹L^-1T³].

Increases with increase in temperature and vice-versa.

Thermoplastics gets deformed easily on heating and can also be bent easily. As a result, they are not used for making frying pan handles. Frying pan handles are made with thermosetting plastics which are resistant to fire and can tolerate heat better than other plastics.

Synthetic fibres become more popular than natural fibres because they are cheaper than natural fibres. The raw materials for synthetic fibres are mainly petrochemicals such as coal. Hence, the manufacturing of synthetic fibres helps in the conservation of forests. Synthetic fibres are used in the manufacture of a variety of household articles such as ropes, buckets, furniture, containers, etc. to highly specialized uses in air crafts, ships, space crafts, healthcare, etc.

Frying pan handles are made with thermosetting plastics which are resistant to fire and can tolerate heat better than other plastics. For example, Bakelite is a thermosetting plastic which is a poor conductor of heat and electricity.

Melamine is a thermosetting plastic. The plastics which when moulded once, cannot be softened by heating are called thermosetting plastics. Melamine is a thermosetting plastic which is resistant to fire and can tolerate heat better than other plastics. It is used to make floor tiles, kitchenware and fire resistant fabrics.

We must try to Reduce, Reuse, Recycle and recover the use of plastic items. We must develop the habits which are environment friendly. 

In order to achieve this, we must try to do the following:

• We must take a cotton carry bag or a jute bag while shopping. 

• We must try to minimize the use of plastic materials. 

For example, we must use a steel lunch box or steel containers instead of plastic ones. 

• We must not throw plastic in the water bodies or on the roads.

Convex mirror (since the focal length of convex mirror is taken as positive).

When the snow accumulates on the wings of an aeroplane, the upper surface of the wing becomes flat. It means the curvature of the surface decreases. Pressure difference which causes the lift off of the Aeroplane depends on the curvature of the wing. So, due to the decrease in curvature, the lift off of the aeroplane also decreases.

Increases with decrease in temperature and vice-versa.

Plastic is a polymer like a synthetic fibre. The arrangement of units in a plastic can be linear or cross-linked. The plastics which gets deformed easily on heating and can be bent easily are called thermoplastics. 

For example, polythene and PVC are thermoplastics. These are used in the manufacturing of toys, combs and different types of containers.