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

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🟢 Section A: Very Short Answer – Answers

1. Synthetic fibre: Fibres made by humans using chemical substances are called synthetic fibres.
2. Fibre from wood pulp: Rayon.
3. Artificial silk: Rayon.
4. Thermoplastic example: Polythene.
5. Plastic for switches: Bakelite.

🟡 Section B: Short Answer – Answers

1. Why rayon is semi-synthetic:
   Rayon is made from natural raw material (wood pulp) but processed chemically. Hence, it is called semi-synthetic.
2. Two properties of synthetic fibres:
   (i) They are strong and durable.
   (ii) They are wrinkle-resistant.
3. Difference between natural and synthetic fibres:
   Natural fibres are obtained from plants or animals, while synthetic fibres are made by chemical processes.
4. Why plastics should not be burned:
   Burning plastics releases poisonous gases which pollute air and harm living beings.
5. Biodegradable and non-biodegradable substances:
   Biodegradable substances decompose naturally, whereas non-biodegradable substances do not decompose easily.

🔵 Section C: Fill in the Blanks – Answers

1. Nylon fibre is obtained from petroleum.
2. Plastics are non-biodegradable in nature.
3. Bakelite is a thermosetting plastic.
4. Rayon resembles silk.
5. Plastic bags cause environmental pollution.

🟣 Section D: MCQs – Answers

1. Strongest fibre:
   Answer: (c) Nylon
2. Plastic used for non-stick cookware:
   Answer: (c) Teflon

🔴 Section E: Long Answer – Answers

1. Types of synthetic fibres:
   Rayon, nylon, polyester, and acrylic are common synthetic fibres. They are strong, durable, and easy to maintain.
2. Advantages and disadvantages of plastics:
   Advantages: Lightweight, durable, waterproof.
   Disadvantages: Non-biodegradable and pollute the environment.
3. Why plastic is a threat:
   Plastic does not decompose easily, blocks drains, harms animals, and pollutes land and water.

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✅ Practice answers carefully for exam success