Draw a well-labelled diagram of a flame. Explain why each zone has different combustion.

A flame is defined as the area of combustion of a combustible substance.

Generally, the different zone (colour) and combustion of a candle depend on three factors:

1. Nature of the substance that undergoes combustion.

2. Amount of oxygen.

3. Temperature.

A flame consists of three zones, and all three zones of a flame have different colours and different temperature. They are given below:

1. Outer Zone - This zone is blue in colour and has the highest temperature in the flame. It is the hottest part of the flame because complete combustion of the fuel takes place in this zone due to plenty of air around it.  It is quite thin as compared to the middle zone.

2. Middle Zone - This zone is yellow and orange in colour and has a moderate temperature. It is a bright and luminous part of the flame because partial combustion of the fuel takes place due to not getting enough air to burn. Also, this partial burning of the fuel produces carbon particles and leave the flame as smoke and soot. 

3. Innermost Zones -  This zone is dark or black in colour and has the least temperature. It is the coldest part of the flame because no combustion takes place in this zone due to unburnt vapours of the combustible material.