CBSE Class 8 Answered

• It is a man-made fibre prepared from a natural raw material called the cellulose, by chemical treatment.
• The cellulose required for making rayon is obtained from the wood pulp.
• So, rayon is obtained by the chemical treatment of wood pulp.
• Threads are prepared from it with the help of machines. These threads have shine and strength, and they are known as ‘synthetic or artificial silk’.

Ans.3

     Uses of Polythene and PVC: It is used in manufacturing toys, combs, various types of containers, etc

     Uses of Bakelite: Bakelite is a poor conductor of heat and electricity. So; it is used for making electrical switches, handles of various utensils, etc.

    Uses of melamine: Melamine is a versatile material and can resist fire and tolerate heat better than other  plastics. So, it is used for making floor tiles, kitchenware and fabrics which resist fire.

 Ans. 4

• Avoid the use of plastics as far as possible and make use of bags made of cotton or jute.
• The biodegradable and non-biodegradable wastes should be collected and disposed separately.
• Most of the thermoplastic wastes can be recycled.
• As a responsible citizen, remember the 3R principle.

 Ans. 5

Dupont is the material suitable for workers in metal and chemical industries because it protects against the fire, heat or electric arc.