Page 37 - Science Class 08

2. Which of the following is not a natural fibre?
(a) Wool (b) Silk

(c) Nylon (d) Co on
3. Which of the following is not a property of plas cs?
(a) Light (b) Flexible

(c) Highly reac ve (d) All of these
4. Which of the following is not an example of thermoplas c?
(a) Polyvinyl Chloride (b) Nylon
(c) Terylene (d) Silk

5. Which of the following plas c is transparent?
(a) Polyvinyl Chloride (b) Teflon
(c) Bakelite (d) All of these

B. Fill in the blanks.
1. Silk is obtained from ____________ .
2. Naturally occurring polymers are called ____________ .
3. The main source of plas c is ____________ .

4. ____________ plas cs cannot be so ened again on hea ng and cannot be moulded
for the second me.

5. Rayon fibre consists of purified ____________ in the form of long fibres.
C. Write True or False.
1. Terylene is also a synthe c polymer.

2. Bakelite is an example of thermose ng plas cs.
3. Plas cs are insulated materials.
4. Plas cs are non-biodegradable materials that may cause harm to our environment.
5. Nylon was the first synthe c fibre made by man.

D. Match the following columns.
Column I Column II
1. Polythene a. Coverings of electric wires
2. Polyvinyl Chloride b. Plugs and switches

3. Polystyrene c. Wind screen
4. Perspex d. Making of pouches
5. Teflon e. Packaging materials
6. Bakelite f. Non-s ck cook ware
E. Very short answer ques ons.

1. Give two examples each of natural and synthe c fibres.
2. What is a polymer?
3. Why is rayon called a regenerated fibre?
4. List two disadvantages of synthe c fibres.

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