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.

(a) If electrical equipment is on fire, water being a good conductor, may conduct electricity and harm those trying to douse the fire. Hence, water is not a good alternative to stop such fires. Instead, carbon dioxide (CO₂) is the best extinguisher of fires involving electrical equipment.

(b) LPG is a better domestic fuel than wood because :

1. LPG doesn't produce smoke and causes less pollution. Wood on the other hand produces lots of smoke and causes more pollution.
2. No cutting of trees is required to produce LPG whereas wood is obtained by cutting trees which leads to deforestation.
3. LPG has a higher calorific value of 55000 kJ/kg whereas wood has a lower calorific value ranging between 17000 and 22000 kJ/kg.
4. LPG is easier to store and transport whereas wood requires a lot of storage space and transport is difficult due to more weight.
5. Ignition temperature of LPG is low and that of wood is high.

(c) Paper by itself catches fire easily because it has low ignition temperature. When a piece of paper is wrapped around an aluminium pipe and heated, its ignition temperature is not attained so soon because the heat supplied is absorbed by the aluminium pipe. Hence, it does not catch fire easily.