Question

The________
zone of candle is the zone of no combustion.
and coal causes
of air.​

Answer 1

Answer:

the inner zone of the candle which is black in colour is the coolest part of the flame because no combustion takes place in this zone

Answer 2

Answer:

The central zone in a candle flame is the zone of no combustion and coal causes of air.​

Explanation:

The yellow colour region which is the bright part of the flame is the middle zone. It is moderately hot and partial combustion of fuel takes place. The least hot region of the flame is present innermost. This inner zone is black due to the presence of unburnt wax vapours.