(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 is a better domestic fuel as it does not produce smoke and unburnt carbon particles, which cause respiratory problems.
(c) A piece of paper wrapped around aluminium pipe does not catch fire easily. This is
because aluminium, being a metal, is a good conductor of heat. Therefore, heat is transferred from the paper to the metal and the paper does not attain its ignition temperature.