Question

how is a solution with ph 4 related to a solution with ph 5?
the ph 4 solution has 10 times as much h⁺ as the ph 5 solution.
the ph 4 solution has 10 times less h⁺ than the ph 5 solution.
the ph 4 solution has 4 times as much h⁺ as the ph 5 solution.
the ph 4 solution has 100 times as much h⁺ as the ph 5 solution.

Explanation:

The pH scale is logarithmic, where $pH = -\log_{10}[H^+]$. For a solution with pH 4, $[H^+]_1 = 10^{-4}\ M$. For a solution with pH 5, $[H^+]_2 = 10^{-5}\ M$. To find the ratio of $[H^+]$ between the two solutions, we calculate $\frac{[H^+]_1}{[H^+]_2}=\frac{10^{-4}}{10^{-5}} = 10$. So the pH 4 solution has 10 times as much $H^+$ as the pH 5 solution.

Answer:

The pH 4 solution has 10 times as much $\text{H}^+$ as the pH 5 solution.