Question

The $pH$ of a ${10}^{-9}M$ solution of $HCl$ in water is :

• A. $8$
• B. $-8$
• C. Between $7$ and $8$
• D. Between $6$ and $7$

Answer 1

The correct option is D Between $6$ and $7$

As the solution is acidic $pH<7$.

This is because $\left[H^{+}\right]$ from $H_{2}O\left[{10}^{-7}M\right]$ cannot be neglect in comparison to ${10}^{-10}M$