Question

Effluent from an industry A has a pH of 4.2. The effluent from another industry B has double the hydroxyl $\left(O{H}^{-}\right)$ ion concentration than the effluent from industry A. pH of effluent from the industry B will be_____

• A. 4.5

Answer 1

The correct option is A 4.5
$pH=4.2$

$\Rightarrow [H^{+}{]}_A={10}^{-4.2}$

$\Rightarrow [O{H}^{-}{]}_A={10}^{-9.8}$

$\Rightarrow [O{H}^{-}{]}_B=2\times {10}^{-9.8}$

$\Rightarrow pO{H}_B=9.0-log2$

$\Rightarrow p{H}_B=4.50$