Question

To make a solution of $pH=12$, the amount of $NaOH$ dissolved in one litre of solution should be:

• A. $0.1g$
• B. $0.2g$
• C. $0.4g$
• D. $1.2g$

Answer 1

Answer: (C)

$0.4g$

For a solution of $pH=12,$

$pOH=14-12=2$

$\therefore$ $\left[O{H}^{-}\right]={10}^{-2}N=0.01N$

$\therefore$ Weight of $NaOH$ present in $1L$ of the solution is $=strength\times eq.wt.=0.01\times 40=0.4g$

Hence, option $C$ is correct.