A wax candle burns with yellow flame. Give reason.

Hint: Wax is an organic molecule. These are hydrocarbon compounds with long aliphatic chains. Wax is a lipophilic, malleable solid. Their melting point is about \[{\text{4}}{{\text{0}}^{\text{0}}}{\text{C}}\]. Liquid wax is a low viscosity liquid. Wax is insoluble in water and soluble in organic non polar solvents.

Complete step by step solution:
During burning of wax , in the flame different zones of combustion is created. This different flames are,
1. Outermost zone: This is the hottest part of the flame. This part is blue in colour.
2. Middle zone: This part is moderately hot and yellow in colour.
3. Innermost zone: this part is least hot. The colour of this is black.
Burning of wax is burning low energy fuel in a low oxygen content. The incomplete burning of wax produces small unburnt carbon particles. When wax burns the unburnt carbon atoms get heated and form a luminous yellow flame.

Note: The type of flame is depending upon the oxygen amount available for burning. If a sufficient amount of oxygen is present then an oxidizing flame is produced. The colour of oxidizing flame is blue. One the other hand if low amount oxygen is present the reducing flame is produced. The color of reducing flame is yellow.