Question

Two solutions A and B have pH 5 and 9 respectively. Which solution has a higher hydrogen ion concentration? Why?

Answer 1

pH is defined as the negative of the logarithm of the hydrogen ion concentration.
pH = -log[H⁺]
Since there is negative outside , so higher the concentration of H⁺​ , lower is the pH and vice-versa.
Now, Out of these two solution, A is having 5 and B is having 9 pH. Since A is having low pH than B, therefore A will have high H⁺​ concentration. Also, solution with pH less than 7 are said to be acidic, that is, have high H⁺ concentration than the solution with pH more than 7.
By the above formula, [H⁺] concentration of Solution A and B are 10 ^-5 and 10^-9 respectively.