Fill in the blanks:

Burning of wood and coal causes ………… of air.

A liquid fuel used in homes is …………………

Fuel must be heated to its ……………. Before it starts burning.

Fire produced by oil cannot be controlled by……………….

Burning of wood and coal causes air pollution. This is because their combustion releases carbon monoxide (CO), carbon dioxide (CO₂), and unburnt carbon particles into the air.

In homes, a common liquid fuel is LPG (Liquefied Petroleum Gas), which comes in cylinders used for cooking. LPG is considered a better fuel than wood or coal because:

• It is cheaper and easily available.
• It produces more heat energy than wood and coal.
• It causes less pollution, as it burns more cleanly.

For any fuel to burn, it must be heated to its ignition temperature.

• Ignition temperature is the minimum temperature at which a substance catches fire.
• This is a necessary condition for burning to begin.

Fires caused by oil cannot be controlled with water.

• Since oil is lighter than water, water sinks below the oil.
• This does not lower the oil’s temperature, so the fire continues to burn.