Question

Fill in the blanks.​
(a) Burning of wood and coal causes ______ of air. ​
(b) A liquid fuel, used in homes is ______.
(c) Fuel must be heated to its ______ ______ before it starts burning.
(d) Fire produced by oil cannot be controlled by ______.

Answer 1

(a) The burning of wood and coal causes pollution of air.

That is, burning of wood and coal gives a lot of smoke. This can cause air pollution. ​

(b) A liquid fuel used in homes is kerosene.​

Kerosene is a fossil fuel derived from petroleum.​

(c) Fuel must be heated to its ignition temperature before it starts burning.​

The lowest temperature at which a​ substance catches fire is called its​ ignition temperature.​

(d) The fire produced by oil cannot be controlled by water.​

Water is heavier than oil. Hence, it​

sinks below the oil, and oil keeps burning on the top. Therefore, water cannot be used to extinguish fire produced by oil.​