Question

The number of ${OH}^{-}$ ions in 10 mL solution of $pH=3$ is $6.023\times {10}^{x}M$. The value of $x$ is:

• A. 9
• B. 10
• C. 12
• D. 23

Answer 1

The correct option is B 10

Given that

Volume $=10ml$

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

$-log\left[O{H}^{-}\right]=11;\left[O{H}^{-}\right]={10}^{-11}M$

So, no of ions in 10 ml $=0.01\times {10}^{-11}\times N_A=6.023\times {10}^{10}$

So, value of $x$ is 10.