Why does an atomic number not change during a chemical reaction.

One of the following does not happen during a chemical reaction. Thus is:

Why does heat get released // absorbed during chemical reactions?

Why does lead chloride get precipitated during the chemical reaction lead nitrate and sodium chloride ?

A : At equilibrium concentration of the reactant and product does not change with time for a chemical reaction. R : The rate of reaction is zero at equilibrium

Statement-1 : During a chemical reaction total moles remains constant. Statement-2 : During a chemical reaction total mass remains constant.