What is the $\mathrm{pH}$ of $0.02 \mathrm{M} \mathrm{NaOH}$ solution?

What is the $\mathrm{pH}$ of $0.02 \mathrm{M} \mathrm{NaOH}$ solution?
  1. 10.3
  2. 11.3
  3. 11.7
  4. 12.3

Solution

$[\mathrm{NaOH}]=\left[\mathrm{OH}^{-}\right]=2 \times 10^{-2} \mathrm{M}$ $\mathrm{NaOH}$ is strong Base. $\begin{aligned} & \mathrm{P}^{\mathrm{OH}}=-\log \left[\mathrm{OH}^{-}\right]=-\log \left(2 \times 10^{-2}\right) \\ & =2-\log 2 \\ & =2-0.3=1.7 \\ & \mathrm{P}^{\mathrm{H}}+\mathrm{P}^{\mathrm{OH}}=14 \\ & \mathrm{p}^{\mathrm{H}}=14-\mathrm{P}^{\mathrm{OH}}=14-1.7=12.3 \end{aligned}$

Asked in: MHT CET 2021 (21 Sep Shift 1)

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