Question

The pH of a 0.001 M aqueous solution of sodium hydroxide will be:

• A. 5
• B. 7.5 ,
• C. 9
• D. 11

Answer 1

The correct option is D 11

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

Given $\left[O{H}^{-}\right]={10}^{-3}M$ $=-log\left({10}^{-3}\right)$

$pOH=+3$

$pH=14-pOH=14-3=11$

Option D is correct.