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?

Answer : The coefficients are placed in front of the reactants or products.

Explanation :

Balanced chemical reaction : It is defined as the reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.

If the amount of atoms of each type on the left and right sides of a reaction differs then to balance the equation by adding coefficient in the front of the elements or molecule or compound in the chemical equation.

The coefficient tell us about that how many molecules or atoms present in the chemical equation.

For example :

The unbalanced chemical reaction is,

This reaction is an unbalanced chemical reaction because in this reaction number of hydrogen atoms are not balanced.

In order to balance the chemical equation, the coefficient '2' put before the and we get the balanced chemical equation.

The balanced chemical reaction will be,

first one is the correct answer

the answer is na (sodium)