Answer : The coefficient of
used is, 19
Explanation :
Law of conservation of matter : It states that the number of atoms of each element on reactant side should be equal to the product side in the chemical reaction.
In the unbalanced reaction, the number of atoms of hydrogen and carbon is balanced but the number of atoms of oxygen are not balanced. As, there are 2 number of atoms of oxygen on reactant side and there are 38 number of atoms of oxygen on product side. So, for the balanced oxygen we multiply the reactant oxygen by the whole number 19.
The given balanced reaction will be,

Hence, the smallest whole-number coefficient of used for balanced chemical reaction is, 19