If the amount of atoms of each type on the left and right sides of a reaction differs, what must be done to balance it?
subscripts are placed in the chemical formulas
superscripts are placed in the chemical formulas
coefficients are placed in front of the reactants and/or products
it should be left alone

Option (c) is the correct answer.

Explanation:

In order to balance a chemical reaction equation, there must be equal number of reactants and products.

So, when the reactants and products are not equal then coefficients must be placed on both the sides in order to balance them.

For example, is not a balanced equation as number of reactants and products are not the same.

Therefore, to balance the equation multiply by 3 and multiply by 2.

Hence, the equation will be balanced as follows.

Thus, we can conclude that if the amount of atoms of each type on the left and right sides of a reaction differs, then to balance it coefficients are placed in front of the reactants and/or products.