Question

solutions with a ___ concentration of hydrogen ions have a low ph.

a. high

b. low

Explanation:

The pH scale is related to the concentration of hydrogen ions ($\ce{H+}$) in a solution. The formula for pH is $\text{pH} = -\log_{10}[\ce{H+}]$, where $[\ce{H+}]$ is the hydrogen ion concentration. When the hydrogen ion concentration is high, the value of $-\log_{10}[\ce{H+}]$ is low (since the logarithm of a larger number is larger, and we have a negative sign). For example, a solution with a high $[\ce{H+}]$ (like 0.1 M, which is $10^{-1}$ M) has a pH of 1 (low pH), while a solution with a low $[\ce{H+}]$ (like $10^{-14}$ M) has a pH of 14 (high pH). So solutions with a high concentration of hydrogen ions have a low pH.

Answer:

a. high