Question

Addition of water to this solution will not change $\left[H_3{O}^{+}\right]$.

• A. Chemical pH indicator
• B. Acid/base buffer
• C. Anhydrous solution
• D. Hypotonic solution

Answer 1

The correct option is B Acid/base buffer

Addition of water to $X$ solution does not change the $pH$ of the solution, which means the concentration of the species present changes in such a way that the $pH$ remains the same. This is possible for acid/base buffer.

$pH=p{k}_a+\log \frac{\left[salt\right]}{\left[acid\right]}$

Since the volume changes the same for both salt and acid, the ratio $\frac{\left[salt\right]}{\left[acid\right]}$ remains the same and hence $pH$ also remains the same. Same in the case of basic buffer solution.