CBSE Class VIII Science Solutions

Displaying 5 out of 32 questions & answers.
Q1.

Tick (√) the correct option:

  1. A polymer is long chain of
    1. molecules
    2. atoms
    3. fibre
    4. yarn
  2. Cotton is a
    1. synthetic fibre
    2. natural fibre
    3. non-biodegradable fibre
    4. none of the above
  3. Synthetic fibres are obtained by chemical processes involving
    1. two substances
    2. three substances
    3. two or more substances
    4. five substances
  4. The name of the synthetic fibre 'Nylon' is derived from two cities:
    1. New Amsterdam and London
    2. New Orleans and London
    3. New Delhi and London
    4. New York and London
  5. Which of the following polymer is found in human body?
    1. DNA
    2. Vitamins
    3. Ribosome
    4. Nucleus
  6. Nylon is a polymer material made of
    1. ethylene
    2. ethene
    3. amide
    4. polyamide
  7. What is the synthetic fibre that resembles silk in appearance?
    1. Polyester
    2. Nylon
    3. Rayon
    4. Terylene
  8. PET is used for making
    1. flint glass
    2. waterproof shoes
    3. soft drink bottles
    4. plastics
  9. Optical fibers are made from
    1. fine sand
    2. purified natural quartz
    3. dry ice and sand
    4. polyethene
  10. PVC is a
    1. thermoplastic
    2. thermosetting plastic
    3. plastic
    4. all of the above
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Answer:
S A M P L E
  1. (a) molecules
  2. (b) natural fibre
  3. (c) two or more substances
  4. (d) New York and London
  5. (a) DNA
  6. (d) polyamide
  7. (c) Rayon
  8. (c) soft drink bottles
  9. (b) purified natural quartz
  10. (a) thermoplastic
Q2.

Fill in the blanks:

  1. _____________ kill the pests but do not harm the plants.
  2. Tyre cords are also made from _____________.
  3. _____________ can be replaced by iron, aluminium, wood, glass, cloth, etc.
  4. The raw materials to manufacture polyester are _____________.
  5. Ammonium phosphate is example of _____________ and _____________ fertiliser.
  6. Thermocol is the most common example of _____________.
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Answer:
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  1. Pesticides
  2. nylon
  3. steel
  4. by products of petroleum refineries
  5. nitrogen and phosphorus
  6. thermoplastic polymer
Q3.

Tick (√) the correct and cross (X) the wrong statement:

  1. Animal textiles are commonly made from hair or fur.
  2. There are numerous polymers inside the human body.
  3. Potassic fertilisers should be added in the later stages of plant growth.
  4. Soaps form insoluble scum of calcium and magnesium ions with hard water.
  5. Glass fibres cannot be used in the production of spacesuits.
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Answer:
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Q4.

Match the following:

Column AColumn B
1. Used to make water tanks, pipes(a) Bakelite
2. Used to make radio, telephone sets, television shells(b) Nylon
3. Ropes, mats, carpets(c) Crop protection
4. Light-weight and wrinkle-resistant(d) Protective textile/ Kevlar
5. Agro textiles(e) Coir
6. Bullet proof vests(f) PVC

 

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Answer:
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  1. (f) PVC
  2. (a) Bakelite
  3. (e) Coir
  4. (b) Nylon
  5. (c) Crop protection
  6. (d) Protective textile/ Kevlar
Q5.

Find the odd one out:

  1. Malathian, gamaxene, heptachlor, methyl parathion and urea.
  2. Jute, coir, silk, linen and hemp.
  3. Polythene, formica, melamine and bakelite.
  4. Nylon, rayon, terylene, wool, acrylic and cashmilon
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Answer:
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