Question

The flame of the candle has three zones, the outer zone is blue, the middle zone is yellow and the inner zone is black. Which is correct regarding this?
(This question has multiple correct options)
A. The outer zone is hottest
B. The middle zone is hottest
C. The inner zone is the least hot
D. All the zones have the same temperature

Answer 1

Hint: Try to relate all three zones in flame of candle with their combustion efficiency and colour of flame. Now you can easily answer this question.

Complete step by step answer:

A candle flame is formed because wax evaporates on burning. A candle flame consists of three different zones. Each zone has different temperatures and every zone has different colors and this will help us in understanding the temperatures of each zone -
The first zone is called the Outer zone.
The second zone is called the Middle zone.
The third zone is called the Inner zone.
Due to complete combustion, the outer zone is blue in color. This zone is the hottest in temperature (1400 degree celsius) when compared to the other zones. This blue colored zone is the non luminous part of the flame.
The yellow color region which is the bright part of the flame is the middle zone. It is moderately hot (1000 degree celsius) and partial combustion of fuel takes place.
The least hot region (800 degree celsius) of the flame is the innermost zone. This inner zone is black in color due to the presence of unburnt wax vapors.

Hence, the correct options are A and C .

Note: In a general candle, flame color depends on three factors:
The nature of the substance that undergoes combustion
The amount of oxygen and Temperature
There are two types of flames:
Non luminous flames have incomplete combustion and a bright yellow colour.
Luminous flames have complete combustion and are colourless.