On adding dilute NaCl(aq) in an acidic solution, pH of solution decreases

The statement is not correct. Sodium chloride (NaCl) is a neutral salt and its addition to an acidic solution will not decrease the pH of the solution. The pH of a solution is a measure of its acidity or alkalinity. When a neutral salt like NaCl is added to an acidic solution, it does not react with the acid or donate protons (H+ ions) to the solution. Therefore, it does not increase the acidity of the solution or decrease the pH. Instead, it simply dissolves in the solution without affecting its pH.