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by
2. Answer the following questions.
(a) Why did the need for man-made
materials arise
(b) Which are the natural materials
obtained from plants and
animals?
(C) What is vulcanization ?
(d) Which natural materials are used
to obtain fibres?
Answers
Answer:
a. For several years, humans have been dependant on natural materials to meet their demands. However, there has been a shift towards the use of man made materials as well. Increasing population, deforestation and limited natural resources are some of the reasons due to which the need for man made materials arised. Another reason which led to the increase in the use of man made material was to get a comfortable lifestyle.
b.
Sources
Natural material
Objects
Plants Wood Furniture
Rubber Ballon, tyres etc.
Cotton Clothes
Animals Fur Hats, Sweaters
Leather Handbags, shoes
Silk Sarees
c. Vulcanization is the process carried out for the production of rubber. In this process, raw rubber is heated with a mixture of sulphur and an appropriate additive, at a temperature range of 61.85 C to 141.850C for three to four hours. Sulphur is added to give toughness to rubber.
d. Natural materials obtained from plants and animals are used to obtain fibers. For example, wool and silk are natural materials of animal origin which are used for obtaining fibers. Wool is obtained from the fleece (hair) of sheep or yak and silk is obtained from the cocoons of a silk moth. Cotton and jute are examples of natural materials of plant origin which are used for obtaining fibers.