Question

$pH$ of one litre solution containing 40 gm of $NaOH$ is:

• A. 2
• B. 10
• C. 8
• D. 14

Answer 1

The correct option is D 14

1 L of 40 gm (=1 mol) $NaOH$ (molecular weight $=$ 40) corresponds to 1 M solution.

$\left[O{H}^{-}\right]=1$

$pOH=-log\left[O{H}^{-}\right]=-log\left(1\right)=0$

But $pH+pOH=14$.

Hence, $pH=14-pOH=14-0=14$.

Option D is correct.