Question

Assertion :pH of ${10}^{-8}M$ $HCl$ is not equal to $8$. Reason: $HCl$ does not dissociate properly in very dilute solution.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is C Assertion is correct but Reason is incorrect

For ${10}^{-8}HCl$

$[H^{+}{]}_{total}=[H^{+}{]}_{HCl}+[H^{+}{]}_{water}={10}^{-8}+{10}^{-7}=1.1\times {10}^{-7}$.

It is not equal to $8$ because in this case we also taken into account $\left[H^{+}\right]$ ions from water.