Q79 of 83 Page 58

Out of the following materials:

cotton, nylon, terylene, wool, Pet, acrylic


(a) which materials are polyesters?


(b) which materials is a polyamide?


(c) which material is used as a substitute for wool?


(d) which material is used as a substitute for glass?

(a) Terylene and PET are polyesters. Polyester is the synthetic fibre which contains the organic group similar-to those which give fruits their sweet smell. PET is a very familiar form of polyester. It is used for making bottles and utensils which is replacing materials like glass.

(b) Nylon is a polyamide. Nylon is the first fully synthetic fibre. It was prepared from coal, water and air. It is used for making parachutes and rock climbing ropes.


(c) Acrylic is used as a substitute for wool. It is a synthetic fibre which appears to resemble wool. It is flexible, resistant to moth, oil and chemicals. The clothes made from acrylic are relatively cheap and are available in a variety of colours.


(d) PET is a material used as a substitute for glass. It is a form of polyester. Polyester is the synthetic fibre which is made up of repeating units of a chemical called an ester. Esters are the chemicals which give fruits their smell. PET is used for making bottles, utensils, films and wires.


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76

Match the terms of column A correctly with the phrases given in column B:

Column A


(i) Polyester


(ii) Teflon


(iii) Rayon


(iv) Nylon


Column B


(a) Prepared by using wood pulp


(b) Used for making parachutes


(c) Used to make non- stick cookware


(d) Fabrics do not wrinkle easily

 77

Which plastic is used:

(a) for making uniforms of fire-men fire resistant?


(b) for giving non-stick coating on frying pans?


(c) for making handles of frying pans?


(d) for making insulation of electric wires?


(e) for making electric switches?


(f) for making flexible water bottles?

 78

Which of the following articles made of plastics ‘can be recycled’ and which cannot be recycled’ ? give reasons for your choice?

Telephone instruments, plastic toys, cooker handles, plastic covering on electrical wires, electric switches, ballpoint pens, carry bags, plastic bottles, plastic chairs

 80

The synthetic fibre A is chemically a polyamide whereas the synthetic fibre B contains a large number of ester groups. another synthetic fibre C is made of a polymer D which consists of a number of glucose units joined one after the other.

(a) Which fibre could be (i) terylene (ii) rayon and nylon?


(b) Name the polymer D.


(c) Which fibre (A, B or C) is prepared from a natural raw material?


(d) Which fibre (A, B or C) contains the same type of groups as those in a PET jar?