Synthetic Fibres and Plastics

Q23. Why is nylon used for making parachutes and ropes for rock climbing?

Ans. Nylon is used for making parachutes and ropes for rock climbing because nylon fibre is strong and can hold heavy weight.

Q24. What is polymer?

Ans. Synthetic fibres and plastics, like natural fibres, are made of very large units called polymers. Polymers are made up of many smaller units.

Q25. Define petrochemicals.

Ans. All the synthetic fibres are prepared by a number of processes using raw materials of petroleum origin, called petrochemicals.

Q26. Why should we use a cotton carry bag or jute bag while going for shopping?

Ans. We should use cotton or jute bags while going for shopping in order to minimise the use of plastic bags.

Q27. Why plastic articles are available in all shape and size?

Ans. Plastic articles are available in all possible shapes and sizes because plastic is easily mouldable i.e. can be shaped in any form.

Q28. Why is teflon used for nonstick coating on cookwares?
Or
Which material is used for coating non-stick kitchen wares and why?

Ans. Teflon is used for nonstick coating on cookwares because it is a special plastic on which oil and water do not stick.

Q29. Explain why plastic containers are favoured for storing food.

Ans. Plastic containers are favoured for storing food because of their light weight, lower price, good strength and easy handling.

Q30. What is PET? Write its uses.

Ans. PET is a very familiar form of polyester. It is used for making bottles, utensils, films, wires and many other useful products.

Q31. Give the composition of Polycot and Polywool.

Ans. Polycot is a mixture of polyester and cotton.

Polywool is a mixture of polyester and wool.

Q32. “Tin, aluminium and other metal can are considered non-biodegradable.” Give reason.

Ans. Tin, aluminium and other metal can are considered non-biodegradable because they approximately take 100 to 500 years to degenerate.

Q33. Give two uses of rayon.

Ans. Uses rayon

                         i.        It is mixed with cotton to make bed sheets.

                        ii.        It is mixed with wool to make carpets.

Q34. Suggest some ways in which we can contribute towards reducing the use of plastic materials?

Ans. Ways to reduce use of plastic materials

                         i.        Avoid the use of plastics as far as possible.

                        ii.        Make use of bags made of cotton or jute when you go for shopping.

Q35. Give examples to show that plastics are noncorrosive in nature.
Or
Why are the chemicals in the laboratory stored in plastic containers?
Or
Why are plastic containers used to store chemicals in labs?

Ans. Plastics do not react with water and air. They are not corroded easily. That is why they are used to store various kinds of material, including many chemicals.

Q36. What type of cookware is used in microwave oven and why?

Ans. Special plastic cookware is used in microwave ovens for cooking food. In microwave ovens, the heat cooks the food but does not affect the plastic vessel.

Q37. How is plastic useful in healthcare industry?

Ans. Plastics find extensive use in the health-care industry. Some examples of their use are the packaging of tablets, threads used for stitching wounds, syringes, doctors’ gloves and a number of medical instruments.

Q38. Why is melamine used for making floor tiles, kitchenware and fabrics which resist fire?

Ans. Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resist fire.

Q39. Why electrical wires have plastic covering, and handles of screw drivers are made of plastic?

Ans. Plastics are poor conductors of heat and electricity. That is why electrical wires have plastic covering, and handles of screw drivers are made of plastic.

Q40. Why should recycled plastic not be used for the storage of food?
Or
Why is recycled plastic not suitable for storage of food items?
Or
Can recycled plastics be used in food containers? Why or why not?

Ans. Most of the thermoplastics can be recycled. However, during recycling certain colouring agents are added. This limits its usage especially for storage of food.