Question

a chemical equation is balanced when
a d) the number of atoms of each element is the same in reactants and products.
b b) the total number of ions is the same in reactants and products.
c a) the total number of molecules is the same in reactants and products.
d c) the sum of the coefficients of the reactants is equal to the sum of the coefficients of the products.

Explanation:

The law of conservation of mass states that in a chemical reaction, the mass of the reactants must equal the mass of the products. This is achieved when the number of atoms of each element is the same on both sides of the chemical equation. The number of ions, molecules, or the sum of coefficients don't necessarily have to be equal for the equation to be balanced.

Answer:

A. the number of atoms of each element is the same in reactants and products