Question

The pH of ${10}^{-5}M$ $HCl$ solution if $1$ mL of it is diluted to $1000$ mL is :

• A. $5$
• B. $8$
• C. $7.02$
• D. $6.96$

Answer 1

The correct option is D $6.96$

GIven that, concentration of $H^{+}$ in $1$ mL $={10}^{-5}M$

Concentration of $H^{+}$ in $1000$ mL $={10}^{-8}M$

$\text{pH}=-\text{log}({10}^{-7}+{10}^{-8})=6.96$ (Concentration of $H^{+}$ from dissociation of water $\approx {10}^{-7}M$)