NCERT Class VIII Science Solution: Chapter 3-Synthetics Fibres and Plastics Part 4 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 22:

Fill in the blanks.

  1. A polymer is a chain of many small units joined together which are called ________.
  2. The synthetic fibres are also known as ________ fibres.
  3. The first fully synthetic fibre was ________.
  4. A fibre similar to wool is ________.
  5. A plastic used for making crockery is ________.

Answer:

  1. A polymer is a chain of many small units joined together which are called monomers.
  2. The synthetic fibres are also known as man-made fibres.
  3. The first fully synthetic fibre was nylon.
  4. A fibre similar to wool is acrylic.
  5. A plastic used for making crockery is melamine.

Question 23:

Match items in List A with the items of list B.

Match Items in List a with the Items of List B. (Q)
List AList B
  1. Nylon
  • Non-stick coating
  • PET
  • Electric switches
  • Rayon
  • Parachutes
  • Thermosetting plastics
  • Polyester
  • Teflon
  • Artificial silk

Answer:

Match Items in List a with the Items of List B. (A)
List AList B
  1. Nylon
iii Parachutes
  1. PET
iv Polyester
  1. Rayon
v Artificial silk
  1. Thermosetting plastics
ii Electric switches
  1. Teflon
i Non-stick coating

Question 24:

Unscramble the jumbled words given below, related to synthetic materials.

  1. anory
  2. lopmery
  3. relyteen
  4. laspict
  5. yespolter
  6. felton

Answer:

  1. Rayon
  2. Polymer
  3. Terylene
  4. Plastic
  5. Polyester
  6. Teflon
Natural and Synthetic Materials

LONG ANSWER QUESTIONS

Question 25:

Indicate whether the following statements are true or false. Also write the false statements in their correct form.

  1. The fabric terywool is obtained by mixing Terylene and wool.
  2. Synthetic fibres do not melt on heating.
  3. It is risky to wear synthetic clothes while working in the kitchen.
  4. Most of the plastics are biodegradable.

Answer:

  1. The fabric terywool is obtained by mixing Terylene and wool. (True)
  2. Synthetic fibres do not melt on heating. (False)

Hint: Synthetic fibres melt on heating.

  1. It is risky to wear synthetic clothes while working in the kitchen. (True)
  2. Most of the plastics are biodegradable. (False)

Hint: Most of the plastics are non-biodegradable.

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