Question

If the pH of an aqueous solution of base is $12$, the concentration of hydroxide ion in $\text{mol/L}$ will be:

• A. $2$
• B. ${10}^{-12}$
• C. ${10}^{-2}$
• D. ${10}^{-1}$

Answer 1

The correct option is C ${10}^{-2}$

We know, $pH+pOH=14$
Since given $pH=12$, then $pOH=14-12=2$
$\because pOH=-\log \left[O{H}^{-}\right]\Rightarrow 2=-\log \left[O{H}^{-}\right]\Rightarrow \left[O{H}^{-}\right]={10}^{-2}=0.02\text{mol/L}$