Question

If the pH of pure water is $7$, then the hydrogen ion concentration, $\left[H^{+}\right]$ in mol L${}^{-1}$ will be:

• A. ${10}^{-7}$
• B. $0$
• C. $7$
• D. ${10}^{+7}$

Answer 1

Answer: (A)

${10}^{-7}$

We know that $pH=-log\left[H^{+}\right]$

Given, $pH=7$

So, $7=-log\left[H^{+}\right]$

$log\left[H^{+}\right]=-7⟹\left[H^{+}\right]={10}^{-7}$

Hence, the hydrogen ion concentration is ${10}^{-7}$ mol L${}^{-1}$.