What is $\left[{\mathrm{H}}^{+}\right]$ in a solution that is $0.01\mathrm{ }\mathrm{M}$ in $\mathrm{H}\mathrm{C}\mathrm{N}$ and $0.02\mathrm{ }\mathrm{M}$ in $\text{NaCN?}$
br /> $({\mathrm{K}}_{\mathrm{a}}$for $\mathrm{H}\mathrm{C}\mathrm{N}=6.2\times 10^{-10})$

• A

  $3.1\times 10^{10}$
• B

  $6.2\times 10^5$
• C

  $6.2\times 10^{-10}$
• Correct answer
  D

  $3.1\times 10^{-10}$

Hence, the correct answer is option: 'D'.