8th CBSE Science Unit 3 Synthetic Fibers and Plastics Important Question Paper | QB365

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8th CBSE Science Unit 3 Synthetic Fibers and Plastics Important Question Paper

Published on: 27/07/2019

Synthetic Fibers and Plastics

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Questions:

Generic 3

3 x 3 = 9

Write disadvantages of plastics.

A bucket made up of plastic does not rust like a bucket made up of iron. Why?

"Manufacturing synthetic fibres is actually helping conservation of forests". Comment.

Match the following

5 x 1 = 5

Plastic bags

Thermosetting

PVC

Acrylic

Polyester

Generic 2

4 x 2 = 8

When we add hot water in a plastic bottle, it gets deformed. What kind of plastic is it? Give two more examples.

10.

Why does plastic find such variety of uses?

11.

The manufacture of which artificial fibres contributes to deforestation?

12.

Write the name of raw materials which are used in making nylon.

Generic 5

2 x 5 = 10

13.

Shruti's mother went to the market to buy new lunch box for Shruti. She saw different lunch boxes made up of plastics as well as steel. Plastic lunch boxes of different colours were very attractive but the steel lunch box was very simple. Shruti's mother told her to select a lunch box for her. She selected a lunch box made of steel instead of plastic one. Her mother purchased the steel lunch box for her.
Read the passage and answer the following questions:
(i) Why does Shruti prefer steel lunch box instead of plastic one?
(ii) Are plastic materials environment friendly? Explain.
(iii) What values are shown by Shruti?

14.

Nikita's mother went to the market to buy new lunch box for Nikita. She saw different lunch boxes made up of plastics as well as steel. Plastics lunch boxes of different colours was very attractive but the steel lunch box was very simple. Nikita's mother told him to select a lunch box for you. She selected a lunch box made of steel instead of plastic one. Her mother purchased the steel lunch box for him.
Read te following passage and answer the following questions.
(a) Why Nikita prefer steel lunch box instead of plastic one?
(b) Is plastic materials environment friendly? Explain.
(c) What values are shown by Nikita?

Multiple Choice Question

5 x 1 = 5

15.

The strongest fibre is called:

(a)

rayon

(b)

nylon

(c)

acrylic

(d)

none of these

16.

Which is not made from nylon?

(a)

socks

(b)

rope

(c)

bottles

(d)

tents

17.

PET is a

(a)

polyester

(b)

nylon

(c)

polyamide

(d)

thermosetting polymer

18.

Polycot is obtained by mixing

(a)

nylon and wool

(b)

polyester and wool

(c)

nylon and cotton

(d)

polyester and cotton

19.

Which of the following is a source of rayon?

(a)

Wool

(b)

PET

(c)

Wood pulp

(d)

Silk

Fill up / 1 Marks

5 x 1 = 5

20.

Plastic does not react with ________ and ________.

21.

__________ and ________ are some of the examples of thermoplastics.

22.

_________ is quite suitable for making dress material.

23.

Plastics are............ conductors of heat

24.

A plastic used for making crockery is.........

True or False

5 x 1 = 5

25.

We should not wear synthetic clothes while cooking in the kitchen or in a laboratory.

(a)

False

(b)

True

26.

Rayon is the fully synthetic fibre.

(a)

True

(b)

False

27.

PVC is thermosetting plastic.

(a)

True

(b)

False

28.

Electric switches, plugs, sockets and handles of cooking utensils are made up of thermoplastics.

(a)

True

(b)

False

29.

Artificial fibres are stronger than natural fibres.

(a)

False

(b)

True

1 Marks

5 x 1 = 5

30.

What is the versatility about melamine?

31.

Name the articles made from PET.

32.

Name any two thermoplastic and thermosetting plastics.

33.

What are natural fibres?

34.

Which is biodegradable? Paper bag or polythene bag?

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Answers Key:

Generic 3

3 x 3 = 9

Plastics take several years to decompose, so they are not environment-friendly. Plastic causes environmental pollution. Besides, the burning process of synthetic material is quite slow and it does not burn completely. In this way, it releases lots of poisonous fumes in the atmosphere causing air pollution.

Plastic is non-reactive material. When left exposed to moisture and air, it does not react with air and water which are essential for corrosion, therefore does not rust

Manufacturing synthetic fibres is actually helping conservation of forests because the natural fibres require raw materials from plants and animals. So, they lead to cutting of trees and killing of animals. On the other hand, synthetic fibres are made of chemicals obtained from coal and petroleum products. Thus, manufacturing of synthetic fibres is actually helping conservation of forests.

Match the following

5 x 1 = 5

()
Non bio-degradable

()
Cannot be softened by heating

()
Polyvinyl chloride

()
Artificial wool

()
Fabrics do not wrinkle easily.

Generic 2

4 x 2 = 8

It is thermoplastic. Two examples are polythene, PVC.

10.

Plastic is easily mouldable, i.e., can be shaped in any form. Plastic can be recycled, reused, coloured, melted, rolled into sheets or made into wires. That is why it finds such variety of uses.

11.

The manufacture of rayon which is obtained from wood pulp contributes to deforestation.

12.

The raw materials used in making nylon are coal, water and air.

Generic 5

2 x 5 = 10

13.

(i) Shruti was aware that plastic is a non-biodegradable material. Disposal of plastic is a major problem. It is not easily decomposed by natural process. So, to avoid the use of plastic she prefers to take steel lunch box.
(ii) No, plastic materials are not environment friendly since, they take several years to decompose and cause environmental pollution. Besides, in the burning process, it releases lots of poisonous fumes (gases) into the atmosphere causing air pollution.
(iii) Shruti is very aware, sensible and intelligent girl.

14.

(a) Nikita was aware that plastic is a non-biodegradable material. Disposal of plastic is a major problem. It is not easily decomposed by natural process. So, to avoid the use of plastic she prefer to take steel lunch box.
(b) No, plastic materials are not environment friendly since, it takes several years to decompose and causes environmental pollution. Besides, in the burning process it releases lots of poisonous fumes (gases) into the atmosphere causing air pollution.
(c) Nikita is very aware, sensible and intelligent girl.

Multiple Choice Question

5 x 1 = 5

15.