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3 Marks Question

  1. Why is glass called the fourth state of matter? Write any two uses of water glass and lead crystal glass.
  2. Glass is always in a liquid state, not solid or gaseous. It is also called a super cooled liquid. So, it is called the fourth state of matter.Glass is always in a liquid state, not solid or gaseous. It is also called a super cooled liquid. So, it is called the fourth state of matter.

    Any two used of water glass are:

    1. To make fire resistance accessories.
    2. To make gum or paste.

    Any two uses of lead crystal glass are:
    1. It is used to make hard glass test tube.
    2. It is used to make lens, prism, etc.
  3. How can you prepare soap? Write with word/formula equation.
  4. Soap can be prepared by treating vegetable or animal oils and fats with a strong base such as sodium hydroxide or potassium hydroxide in an aqueous solution.
    Equation:
    fats/oil + alkali ⟶ soap + glycerol
    C3H5(OOCR)3 ⟶ 3NaOOCR + C3H5(OH)3
    where R = C17H35
  5. Write any two applications of thermosetting and thermoplastics. Mention any two characteristics of plastics.
  6. Applications of thermosetting plastics are:
    1. To make handles of cooker.
    2. To make cup, plates, bowls, etc.
    Applications of thermoplastic are:
    1. To make polythene bags.
    2. To make pipes.
    Characteristics of plastics are:
    1. Bad conductors of heat and electricity.
    2. It is light, do not corrode in air and water, can be recycled.
  7. How is ordinary glass made? Write any one use of ordinary glass.
  8. Ordinary glass is made by fusing a mixture of 50% silica, 15% sodium carbonate, 10% calcium carbonate and 25% glass pieces at 850°C in a special type of tank furnace.

    It is used for making bottles, light bulbs, window panes, etc.

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