Q.5 Give reasons.
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.


Answer :

a) Water is a good conductor of electricity. Thus if water is added to an electrical fire, the water being a good conductor, spreads the electricity further. Hence the person dousing the fire might get an electric shock.

b) LPG is a cleaner fuel than wood as it undergoes complete combustion and doesn’t release smoke and other pollutants. But wood releases a lot of smoke and fumes, thus polluting the atmosphere and leading to various respiratory diseases. Hence, LPG is a better domestic fuel than wood.

c) The paper by itself catches fire easily because it has a low ignition temperature. While a piece of paper wrapped around an aluminium pipe doesn’t catch fire as aluminium is a good conductor of heat, so when the paper has an increase in temperature, it transfers the heat from paper to the aluminium pipe. Hence paper doesn’t catch fire.

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