Class 8 Science – Chapter 3
Synthetic Fibres and Plastics
Worksheet – FULL Answers (Step-by-Step)

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Q1. What are synthetic fibres?

Answer: Synthetic fibres are fibres made by humans using chemical substances. They are not obtained from plants or animals.
Examples: Nylon, Rayon, Polyester, Acrylic.

Q2. Why is rayon called artificial silk?

Answer: Rayon is called artificial silk because it looks like silk and has a shiny appearance like silk, but it is made from wood pulp using chemical treatment.

Q3. Write two uses of nylon.

Answer:
1. Nylon is used to make ropes, parachutes and fishing nets.
2. It is used in making seat belts and toothbrush bristles.

Q4. What is polyester? Write one use.

Answer: Polyester is a synthetic fibre made from chemical substances.
Use: It is used to make clothes, curtains and bedsheets.

Q5. Name two types of plastics.

Answer:
1. Thermoplastics
2. Thermosetting plastics

Q6. What are thermoplastics?

Answer: Thermoplastics are plastics which soften on heating and harden on cooling. They can be moulded again and again.
Examples: Polythene, PVC.

Q7. What are thermosetting plastics?

Answer: Thermosetting plastics are plastics which do not soften when heated once. They cannot be reshaped.
Examples: Bakelite, Melamine.

Q8. Why should plastics be avoided?

Answer: Plastics should be avoided because:
• They are non-biodegradable
• They cause soil and water pollution
• Burning plastics releases toxic gases

Q9. Why is bakelite used for electrical switches?

Answer: Bakelite is a poor conductor of heat and electricity. Therefore, it is safe to use for making electrical switches and plugs.

Q10. Write two advantages of synthetic fibres.

Answer:
1. They are strong and durable.
2. They are lightweight and easy to maintain.

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🌟 Step-by-step answers help students understand concepts clearly