When fire brigade arrives, it pours water on the fire. Water cools the combustible material, so that its temperature is brought below its ignition temperature. This prevents the fire from spreading. Water vapours also surround the combustible material, helping in cutting off the supply of air. So, the fire is extinguished.

Substances that burn with flame are candle, oil lamp.
Substances that burn without flame are coal, charcoal.

If kerosene oil is heated a little, it catches fire. But if wood is heated a little, it does not catch fire because ignition temperature of kerosene oil is lower than that of wood.

When the clothes of a person catch fire the person is covered with a blanket to extinguish fire because blanket cuts off the supply of air, that is the supporter of fire.

Characteristics of an ideal fuel:
(i) It is readily available, cheap and can easily be transported.
(ii) It burns easily, has higher calorific value and does not leave behind any undesirable substances.

We are advised never to sleep in a room with burning coal fire because incomplete combustion of these fuels gives carbon monoxide gas. It is a very poisonous gas, it can kill persons sleeping in that room.

In the sun, heat and light are produced by nuclear reactions.

A fire can be extinguished by removing the heat or by cutting off the air supply to the burning substances.

Fuel efficiency is determined by its calorific value which is the amount of heat energy produced on complete combustion of 1 kg of a fuel. The calorific value of a fuel is expressed in kJ/kg.

One disadvantage of burning a fuel in insufficient supply of air is less heat and hence leads to wastage of fuel.

The different zones of a candle are innermost, middle and outermost zone.

We need to take special care in storing kerosene oil because it has low ignition temperature and it can catch fire easily.

The cutting of trees is called deforestation/

The substances which undergo combustion are called combustible substances.

The substance which provides heat and light is called fuels