1. A person has to make a non-stick pan. He has three types of plastics,Bakelite, Teflon and PVC. Which plastic will he use for coating and why.
Ans:The person will use Teflon because it is not affected by heat and does not react chemically with other substances.

2. Explain one difference between thermoplastic and thermosetting plastics with example.

Thermosetting Thermoplastic
(i) These plastics cannot be moulded and reset.

(ii) e.g.  Bakelite and melamine.

(i) These plastics can be moulded and reset a number of times.

(ii)  e.g. Polythene and PVC.

3. Differentiate between natural and synthetic fibres.
Ans: Natural fibres are obtained from nature, e.g., cotton whereas synthetic fibres are made by man, e.g., nylon.

4. How is rayon made. Give one advantage of using rayon.
Ans: Rayon is obtained from wood pulp by treating it chemically. It is cheaper than silk, but can be woven like silk fibre.

5. Is nylon fibre so strong, that we can use it to make parachutes.
Ans: Yes, nylon is very strong and it can be used for making parachutes.

6. Give some uses of PET.
Ans: PET is used for making bottles, utensils, fibres and wires.

7. Give the composition of Polycot and Polywool.
Ans: Polycot is a mixture of polyester and cotton, Poly wool is a mixture of polyester and wool.

8. What properties of plastics make it useful for many things.
Ans: Plastics can be recycled, reused, coloured, melted, rolled into sheets or made into wires, so they are very useful.

9. Why is melamine used for making kitchenware
Ans: Melamine resists fire and can tolerate heat better than other plastics. So, it is used for making kitchenware.

10. Buckets made up of plastics are better. Why.
Ans: Buckets made up of plastic are better because they are light in weight, strong and durable and they don’t react with normal hot water.

11. Differentiate between biodegradable and non-biodegradable materials.

Biodegradable Materials Non-biodegradable Materials
(i) A material which gets decomposed through natural processes, such as action of bacteria.
(ii) e.g., cotton or jute.
(i) A material which does not get decomposed by natural processes.
(ii) e.g., plastics.

12. Give one use each of Bakelite, nylon and acrylic.
Ans: Nylon is used in textile industry to produce clothes. Acrylic is used as a substitute of natural wool for knitting sweaters, blankets etc.

13. What are Synthetic fibres and how are they synthesized.
Ans: Synthetic fibres are called artificial, man-made fibres. Synthetic fibres are synthesised from raw material called mono or petrochemicals

14: Give three advantages of rayon.
Ans: Advantages of rayon are:
(i) It is cheap. It can be dyed in many colours. It can be woven like silk and durable.

15. What are the advantages of nylon
Ans: Nylon fibre is strong, elastic and light. It is lustrous and easy to wash.