Question

While cooking, if the bottom of the vessel is getting blackened on the outside, it means
that
[A]the food is not cooked completely.
[B]the fuel is not burning completely.
[C]the fuel is wet.
[D]the fuel is burning completely.

Answer 1

[B]the fuel is not burning completely.

Answer 2

Answer - [B] the fuel is not burning completely.

While cooking, if the bottom of the vessel is getting blackened on the outside, it means that the fuel is not burning completely. When the fuel burns completely giving a blue flame, the bottom of the vessel remains clean.