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.
Answers
Answer:-
(a) Water is not used to control fire produced by electrical equipment because water is a good conductor of electricity and may result in electric shock to the person extinguishing the fire.
(b) LPG is a substance which is readily available. It is cheaper than wood and burns easily in air at moderate rate. It does not produce fume and ashes as wood do. Moreover LPG can be stored and transported easily and conveniently.
(c) Paper catches fire easily because of its low ignition temperature, but when it is wrapped around an aluminium pipe, the ignition temperature does not meet as the heat supplied is transferred to the aluminium pipe leaving the paper unburnt.
Explanation:
5 a) Water is a good conductor of electricity. If it is used for controlling a fire involving electrical equipments, then the person dousing the fire might get an electric shock. Also, water can damage electrical equipments.
b)LPG has more calorific value and produces no pollution. So it is better domestic fuel than wood.
(c) The ignition temperature of paper is less, so it catches fire easily. It does not catch fire when wrapped around aluminium pipe because aluminium absorbs the heat, so paper does not attain its ignition temperature.