Question

Number of $O{H}^{-}$ in 1 mL solution of pH = 13 is:

• A. $1\times {10}^{13}$
• B. $6.00\times {10}^7$
• C. $6.00\times {10}^{13}$
• D. $6.02\times {10}^{19}$

Answer 1

The correct option is D $6.02\times {10}^{19}$

$pH=-log\left(\left[H^{+}\right]\right)=13\left[H^{+}\right]={10}^{-13}M$

Now,

$\left[H^{+}\right]\left[{OH}^{-}\right]={10}^{-14}M\therefore \left[{OH}^{-}\right]={10}^{-1}M={10}^{-1}mol{L}^{-1}$

Again,

In 1ml solution moles of $H^{+}$

$=0.1\times {10}^{-3}mol=6.023\times {10}^{23}\times {10}^{-4}molecules=6.023\times {10}^{19}molecules$

Therefore option D is correct.