Question

If the concentration of hydronium ions in a solution is ${10}^{-4}\text{M}$, then the pH of this solution is:

• A. 4

Answer 1

The correct option is A 4
The general relation between the pH and the concentration of hydronium ions is:
$\text{pH}=-{\text{log[H}}_3{\text{O}}^{+}]$
For the given solution concentration of hydronium ions $={\text{[H}}_3{\text{O}}^{+}]={10}^{-4}\text{M}$
Placing the given value into the equation we get,
$\text{pH}=-\text{log}\left({10}^{-4}\right)$
$\text{pH}=4\text{log}10$
$\text{pH}=4$