While cooking, if the bottom of the utensil 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.
(b) the fuel is not burning completely
While cooking, if the bottom of the utensil is getting blackened on its outer side, it means that the fuel is not burning properly, thereby leading to soot formation.