Question

$1.0$ ml of a solution of $HCl$ with a $pH$ of $4.0$ is added it to $9.0$ ml of distilled water, the $pH$ of the final solution will be:

• A. The pH would remain unchanged.
• B. The pH would rise to $5.5$
• C. The pH would rise to $5.0$
• D. The pH would be unmeasurable due to the amount of dilution.
• E. The pH would rise to $7.0$

Answer 1

The correct option is C The pH would rise to $5.0$

$pH$ of given solution = $4$

$\left[H^{+}\right]=$ ${10}^{-4}$

$M_1$ x $V_1$ = $M_2$ x $V_2$

${10}^{-}4$ x $1ml$ = $M_2$ x$(9+1=10)$

$M_2$ = ${10}^{-5}=[H+]$

$pH=-log\left[H^{+}\right]=-log\left[{10}^{-5}\right]=5$
Correct answer is $C$.