Study Materials

NCERT Solutions for Class 8th Science

 

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Chapter 3. Synthetic Fibres And Plastics

Additional Questions With Solutions

 

 

 

Additional Questions With Solutions


Q15: Write the differences between thermoplastics and thermosetting plastic.

Ans:

Thermoplastics plastic

Thermosetting plastic.

 (i) It can be bent.

 (ii) It gets deformed easily on heating.

 (iii) Examples; polythene and PVC.

 (i) It can’t be bent.

 (ii) It can’t be softened by heating.

 (iii) Example; Bakelite and melamine.

Q16: What is Bakelite?

Ans: Bakelite is a thermoplastic. It is a polymer which is a poor conductor of heat and electricity. It is used for making electrical switches, handles of various utensils, etc.

Q17: What is melamine?

Ans: Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resist fire.

Q18: Explain why plastic containers are favoured for storing food.

Ans: plastic containers are favoured for storing food. This is because of their light weight, lower price, good strength and easy handling. Being lighter as compared to metal.

Q19: Give examples which indicate that nylon fibres are very strong.

Ans: Nylon is also used for making parachutes and ropes for rock climbing. A nylon thread is actually stronger than a steel wire.

Q20: Why are the handles of screw driver and fry pan made of plastic?

Ans: Because plastics are poor conductors of heat and electricity.

Q21: Why is the disposal of a plastic material major problem?

Ans: Toxin produced by plastic is major problem to remove from environment. As on burning it produces toxic smoke and disposal in soil it produce toxic effect. So it can’t be removed easily.

Q22: What is biodegradable?

Ans: A material which gets decomposed through natural processes, such as action by bacteria, is called biodegradable.

      Example: peels of vegetables and fruits, paper, wood , cotton clothes etc.

Q23: What is non-biodegradable?

Ans: A material which is not easily decomposed by natural processes is termed as non-biodegradable. For Example: Tin aluminium plastic bags and other metals.

 

 

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