Synthetic Fibres and Plastics - Exemplar Solutions 1

CBSE Class 8 Science
NCERT Exemplar Solution
CHAPTER 03
Synthetic Fibres and Plastic

MULTIPLE CHOICE QUESTIONS

1. Pick the synthetic fibre out of the following?

(a) Cotton

(b) Nylon

(d) Wool

Ans. (b) Cotton and jute are natural fibres obtained from obtained from plants. Wool is obtained from animal. Whereas Nylon is a fibre which is prepared artificially by joining together a series of small units called monomer. These are actually chemical substance which form large units called polymer and hence is called synthetic fibre.

2. Which of the following is a source of rayon?

(a) Wool

(b) PET

(d) Silk

Ans. (c) Rayon is produced from natural cellulose like wood pulp, but it is still considered as synthetic fibre having properties similar to silk because it is obtained by chemical treatment of wood pulp.

3. Polycot is obtained by mixing

(a) nylon and wool

(b) polyester and wool

(d) polyester and cotton

Ans. (d) Polycot is a mixture of polyester and cotton. As the name suggests, it is obtained by mixing two types of fibres.

4. Which is a thermosetting plastic?

(a) Melamine

(b) Polythene

(d) Nylon

Ans. (a) Out of the following melamine is a thermosetting plastic having ability to resist fire and tolerate heat for which it is extensively used to make floor tiles, kitchenware and fabrics used for firemen that can resist fire.

5. The material similar to silk in appearance is

(a) Nylon

(b) Rayon

(d) Terylene

Ans. (b) Rayon is produced from natural source like wood pulp. It is called artificial silk because it has shine and appearance like silk.

6. The most suitable material for the preparation of handles of cooking utensils is

(a) Polythene

(b) PVC

(d) Bakelite

Ans. (d) Bakelite being the poor conductor of heat and electricity is used for making electrical switches and handles of various utensils.

7. Which of the following is not a common property of plastics?

(a) Non-reactive

(b) Light in weight

(d) Good conductor of electricity

Ans. (d) Plastics are poor conductor of electricity and hence extensively used in the manufacture of electrical appliances, handles of utensils, switch boards etc.

8. Which of the following represents the correct match for items in Column A with those in Column B.

Column A	Column B
I. Nylon	(i) Thermoplastic
II. PVC	(ii) Thermosetting plastic
III. Bakelite	(iii) Fibre

(a) I-(ii), II-(iii), III-(i)

(b) I-(iii), II-(i), III-(ii)

(d) I-(iii), II-(ii), III-(i)

Ans. (b) I-(iii) Nylon is a fibre formulated artificially by human beings and hence is a synthetic fibre. It is obtained by joining together a chain of small units that are actually chemical substances to form large units called polymer.

II-(i) PVC is a thermoplastic that gets easily deformed on exposure to heat and can also be bent easily.

III-(ii) Bakelite is a thermosetting plastic and being the poor conductor of heat and electricity is used for making variety of household and electrical items.

9. Which of the following groups contain all synthetic substances?

(a) Nylon, Terylene, Wool

(b) Cotton, Polycot, Rayon

(d) Acrylic, Silk, Wool

Ans. (c) Plastics are also polymers like the synthetic fibres. In option (c) all the substances are plastic and hence synthetic in nature.

PVC is a thermoplastic that gets easily deformed on exposure to heat and can also be easily bent.

Polythene is also a thermoplastic that gets easily deformed on exposure to heat.

Bakelite is a thermosetting plastic and being the poor conductor of heat and electricity is used for making electricity is used for making electrical switches.

10. The material which is commonly used for making kitchen containers is

(a) PVC

(b) Acrylic

(d) PET

Ans. (d) PET is a very familiar form of polyester. It is extensively used as a raw material in the manufacturing of packaging materials such as bottles and containers for packaging materials such as bottles and containers for packing a broad range of food products and many other goods due to its property of being strong, transparent, safe and versatile.