CBSE Class 8 Answered

The different types of combustion on the basis of rate are-

1) Rapid combustion:

A combustion reaction in which large amounts of heat are produced in a short time is called rapid combustion.

Example: Burning matchstick near a gas stove.

2) Spontaneous combustion

A combustion reaction which once started does not require any external heat to proceed further is called spontaneous combustion.

Example: The ignition temperature of white phosphorus is 35 degree celsius. If the room temperature rises above 35 degree celsius, It catches fire immediately; even without being lit by a match stick

3) Explosion

A combustion reaction involving a sudden release of large amounts of energy in the form of heat, light and sound along with gas in a short interval of time  is called an explosion.

Example: On festive days, we often burst fireworks. On igniting the cracker, we observe a sudden release  of light, heat, sound and  gas. Such a combustion reaction is called  an explosion.

4) Slow combustion

Combustion that takes place at a very slow rate is called slow combustion.

Example: During the process of respiration, food reacts with oxygen that is inhaled in our body, to produce carbon dioxide, water and energy. This combustion reaction takes place at body temperature. Rusting of iron is another example of slow combustion. Complete combustion.