Question

The value of pH of a solution is 6. It indicates that the concentration of hydroxyl ion is

• A. ${10}^{-6}\left(gm/lit\right)\text{and the solution is alkaline}$
• B. ${10}^{-8}\left(gm/lit\right)\text{and the solution is acidic}$
• C. ${10}^{-8}\left(gm/lit\right)\text{and the solution is alkaline}$
• D. ${10}^{-6}\left(gm/lit\right)\text{and the solution is acidic}$

Answer 1

The correct option is B ${10}^{-8}\left(gm/lit\right)\text{and the solution is acidic}$

$pH=-lo{g}_{10}\left[H^{+}\right]$

$6=-lo{g}_{10}\left[H^{+}\right]$

$\left[H^{+}\right]={10}^{-6}....\left(1\right)$

We know the relation between $\left[H^{+}\right]$ & $\left[O{H}^{-}\right]$

$\left[H^{+}\right]\left[O{H}^{-}\right]={10}^{-14}$

$\left[O{H}^{-}\right]=\frac{{10}^{-14}}{\left(H^{+}\right)}$

$\left[O{H}^{-}\right]=\frac{{10}^{-14}}{{10}^{-6}}$

$\left[O{H}^{-}\right]={10}^{-8}$

i.e., hydroxl ion concentration is ${10}^{-8}\left(gm/lit\right)$ & the solution is acidic.