If ${\mathrm{pK}}_{\mathrm{a}}=4$ and ${\text{K}}_{\text{a}}={\text{Cα}}^{\text{2}}$, then find van't Hoff factor for a weak HA type acid, when $\mathrm{C}=0.01 \mathrm{M}$.

• A

  $1.01$
• B

  $1.02$
• Correct answer
  C

  $1.10$
• D

  $1.20$

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