NCERT Class VIII Science Solution: Chapter 3-Synthetics Fibres and Plastics Part 3

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Question 15:

Plastic is used for making a large variety of articles of daily use and these articles are very attractive. But it is advised to avoid the use of plastic as far as possible. Why?

Answer:

Due to its non-biodegradable nature it causes environmental pollution.

Image of diffrence between biodegradable waste and non biodegradable

Diffrence between Biodegradable Waste and Non Biodegradable

Image of diffrence between biodegradable waste and non biodegradable

Question 16:

Why is it not advisable to burn plastic and synthetic fabrics?

Answer:

Burning of plastic and synthetic fabrics produces lots of poisonous gases causing air pollution.

Question 17:

Select the articles from the following list which are biodegradable.

  1. Paper

  2. Woolen clothes

  3. Wood

  4. Aluminium can

  5. Plastic bag

  6. Peels of vegetables

Answer:

Question 18:

A bucket made of plastic does not rust like a bucket made of iron. Why?

Answer:

Plastic is a non-reactive material. It does not react with air and water and thus does not rust.

SHORT ANSWER QUESTIONS

Question 19:

Rohit took with him some nylon ropes, when he was going for rock climbing. Can you tell why he selected nylon ropes instead of ropes made of cotton or jute?

Answer:

Nylon ropes are strong, elastic and lighter as compared to cotton and jute ropes.

Image of nylon ropes

Nylon Ropes

Image of nylon ropes

Question 20:

A lady went to the market to buy a blanket. The shopkeeper showed her blankets made of acrylic fibres as well as made of wool. She preferred to buy an acrylic blanket. Can you guess why?

Answer:

Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. They can be easily washed at home.

Question 21:

PVC (polyvinyl chloride) is a thermoplastic and is used for making toys, chappals, etc. Bakelite is a thermosetting plastic and is used for making electrical switches, handles of various utensils, etc. Can you write the major difference between these two types of plastics?

Answer:

Thermoplastics get deformed easily on heating and can be bent easily on heating. On the other hand thermosetting plastics when molded once cannot be softened on heating.