Polymer Chemistry

Samacheer Book Back Questions And Answers For Science Standard 7 Term 3 “Polymer Chemistry“

I. Choose the correct answers:
1. The first man-made fibre is _____.
(a) Nylon
(b) Polyester
(c) Rayon
(d) Cotton

2. Which of the following is the strongest?
(a) Rayon
(b) Nylon
(c) Acrylic
(d) Polyester

3. When you place a natural fibre in a flame it _____.
(a) Melts
(b) Burns
(c) Gets nothing
(d) Explodes

4. A synthetic fibre which has similar properties to wool is _____.
(a) Nylon
(b) Polyester
(c) Acrylic
(d) PVC

5. A good application of plastic is the use of _____.
(a) Blood bags
(b) Plastic cutlery
(c) Plastic straws
(d) Plastic carry bag

6. _____ is non-biodegradable material.
(a) Paper
(b) A plastic bottle
(c) Cotton cloth
(d) Wool

7. PET is the acronym for _____.
(a) Polyester
(b) Polyester and terylene
(c) Polyethylene terephthalate
(d) Polyetheneterylene

II. Fill in the blanks:
1. _____ is an example of polyester fabric.
2. _____ are used to identify different types of plastics.
3. A _____ is a long chain made up of many repeated small units called monomers.
4. The fully natural fibre is called _____.
5. A natural fibre obtained by boiling of cocoons is called _____.

Answers:
1. Raincoat
2. Resin codes
3. Polymer
4. Plant fibre
5. Silk

III. True or False:
1. A lot of plastic pollutes our environment.
2. Refuse (avoid) is the best way to manage plastic.
3. It is good to wear clothes made of synthetic fibres while cooking.
4. Degradable plastics break down into tiny pieces called microplastics.
5. Cotton is a natural polymer.

Answers:
1. True
2. True
3. False (It is good to wear clothes made of fibres while cooking)
4. True
5. True

IV. Match the following:
1. Nylon        A. Thermoplastic
2. PVC           B. Thermosetting plastic
3. Bakelite     C. Fibre
4. Teflon        D. Wood pulp
5. Rayon        E. Non-stick cookwares

Answers:
1. C
2. A
3. B
4. E
5. D

V. Arrange in Correct Sequence:
1. Mix water, starch, vinegar and glycerin in a cooking pot.
2. Let the article cool for 24 hours before we use it.
3. Shape material to form a cup or bowl.
4. Continuously mix on medium heat until the liquid turns clear.
5. When the liquid begins to bubble it is ready to be taken off the stove.
6. Spread the gel onto aluminium foil and cool.

Answers:
1. Mix water, starch, vinegar and glycerin in a cooking pot.
2. Continuously mix on medium heat until the liquid turns clear.
3. When the liquid begins to bubble it is ready to be taken off the stove.
4. Spread the gel onto aluminium foil and cool.
5. Shape material to form a cup or bowl.
6. Let the article cool for 24 hours before we use it.

VI. Analogy:
1. Cotton: natural:: Polyester: _____
2. PLA spoon :compostable:: Plastic spoon: _____
3. Nylon: melts on heating:: Silk: _____

Answers:
1. Synthetic
2. Disposable
3. Burns on heating

VII. Assertion – Reason type question:
1. Assertion (A): Vegetable peels buried in the soil disappear within two weeks.
Reason (R): Vegetable peels are compostable.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

2. Assertion (A): It takes a very long time for nylon clothes to breakdown into microfibers but cotton clothes need only six months to decompose.
Reason (R): Nylon made out of petrochemicals is non-biodegradable and cotton cloth is biodegradable.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

3. Assertion (A): It is good to avoid plastics.
Reason (R): Plastics end up polluting the environment.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

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