Science Question Answer (3 Marks)

1. Plastic is non-biodegradable. It takes several years for plastic to decompose. When thrown in the water drains or in sewers it results in choking of the drains. Therefore, we must avoid the use of plastic as much as possible.
2. Plastic bags thrown in the garbage can be swallowed by the animals such as cows. It can result in choking their respiratory system and can be fatal. Therefore, we must avoid the use of plastic as much as possible.

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.

Modern healthcare would not be possible without the use of plastic materials. Plastics can be used in healthcare in the following ways:

• Plastics are used in the packaging of tablets, syringes, doctor’s gloves and a number of medical instruments.
• Threads used for stitching wounds are made of medical instruments.
• Plastics are used for making intravenous blood bags and heart valves as well.

Synthetic fibers become more popular than natural fibers because they are cheaper than natural fibers. The raw materials for synthetic fibers are mainly petrochemicals such as coal. Hence, the manufacturing of synthetic fibers helps in the conservation of forests. Synthetic fibers are used in the manufacture of a variety of household articles such as ropes, buckets, furniture, containers, etc. to highly specialized uses in aircrafts, ships, space crafts, healthcare, 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 fibers can also be woven like those of natural fibers. It is cheaper than silk but can be woven like silk fibers. It can also be dyed in a variety of colours.

Plastic is a polymer like a synthetic fibre. The arrangement of units in a plastic can be linear or cross-linked. Plastic containers are preferred for storing food because of the following reasons:

• Plastic is non-reactive. It does not react with water and air. It is therefore, safe to keep food in plastic containers.
• Plastic is light, strong and durable and can be molded into different shapes and sizes. It is cheaper than metals. It is widely used in making household items including food containers.
• Plastics are poor conductors of heat and electricity and can be used for making handles of frying pans.

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 fibers 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.

The disposal of plastic wastes is a major problem because of the following reasons:

1. Plastic is non-biodegradable. It takes several years for plastic to decompose and it is not environment-friendly.
2. It causes environmental pollution.
3. The disposal of plastic wastes is a major problem. Plastics cannot be burnt because they release poisonous gases.
4. Plastic bags thrown in the garbage can be swallowed by the animals such as cows. It can result in choking their respiratory system and can be fatal. Therefore, we must avoid the use of plastic as much as possible.

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.

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 molded 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.

Melamine and Bakelite are 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.
Polythene and poly vinyl chloride are 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.

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 fibers:

• Synthetic fibers 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 fibers are used to make dress materials.

The handle and bristles of a toothbrush should be made of different type of plastic material. The handle of toothbrush should be hard and strong whereas the bristles should be soft and flexible.
Thus, the handle is made of plastic while the bristles are made of nylon.

A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable.Following are the biodegradable materials:
Woollen clothes, paper, peels of vegetables and fruits, Cotton cloth and Jute bag. A material which is not easily decomposed by natural processes is termed as non-biodegradable. Following are the non-biodegradable materials: Polythene bags, Aluminium cans, Toothbrush, Electric switch and Frying pan handle.

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 molded 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.

Plastic is non-biodegradable. It takes several years for plastic to decompose and it is not environment friendly. It causes environmental pollution.
Following are the ways to save the environment from excessive plastic wastes:

• We must try to Reduce, Reuse, Recycle and recover the use of plastic items. We must develop the habits which are environment friendly.
• We must not throw plastic in the water bodies or on the roads.
• 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.

The plastics which when molded 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. Hence, electric witches, plugs and sockets made of thermosetting plastics.

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.

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.

Bakelite is a thermosetting plastic. The plastics which when molded 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.

3R's principle in the context of use of plastics means we must try to Reduce, Reuse and Recycle the use of plastic items. We must develop the habits which are environment-friendly. In order to achieve this, we must not throw plastic in the water bodies or on the roads. 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.

Polyester is the synthetic fibre which is made up of repeating units of a chemical called an ester. Esters are the chemicals which give fruits their smell. Polycot, poly wool and terry cot are popular polyesters. These are made by mixing two types of fibers. For example, polycot is a mixture of polyester and cotton. Poly wool is a mixture of polyester and wool. Fabrics made from polyester does not get wrinkled easily. It remains crisp and easy to wash. Hence, it is suitable for making dress material.

Synthetic fibers are man-made fibers 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 fibers. 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.

The use of plastic has a bad effect on the environment because it is non-biodegradable. It takes several years for plastic to decompose and it is not environment friendly. It causes environmental pollution. Also, the burning process of synthetic material is quite slow and it does not get completely burnt easily. It releases lots of poisonous fumes into the atmosphere when burned and causes air pollution.

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 non-biodegradable. It takes several years for plastic to decompose and it is not environment friendly. It causes environmental pollution. Also, the burning process of synthetic material is quite slow. It does not get completely burnt easily. It releases lots of poisonous fumes into the atmosphere when burned and causes air pollution.

Melamine is a thermosetting plastic. The plastics which when molded 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.

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 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. It is used to make electrical switches and handles of utensils.

We should buy cotton shirts to wear in summers. This is because cotton absorbs sweat from our body and allows it to evaporate into the air. It also discourages the growth of bacteria and does not cause any skin allergies.