In order to understand the structure of a flame, light a wax candle and watch its flame. Carefully note the different coloured zones in the flame. Starting from the base of the flame, a flame has three zones. Check the below figure and try to answer the following question

Expalin why dark zone is the coldest part of a candle flame.

Explanation

In the zone of no combustion, the wax vapours coming from the candle do not burn at all due to the absence of oxygen. Hence, it is called the coldest part of the flame.