MCQ
$0.2$  molar solution of formic acid is ionized $3.2\%$. Its ionization constant is
  • A
    $1 \times {10^{ - 12}}$
  • $2.1 \times {10^{ - 4}}$
  • C
    $1.25 \times {10^{ - 6}}$
  • D
    $1 \times {10^{ - 14}}$

Answer

Correct option: B.
$2.1 \times {10^{ - 4}}$
(b) ${K_a} = C{\alpha ^2} = 0.2 \times {\left( {\frac{{3.2}}{{100}}} \right)^2} = 2.048 \times {10^{ - 4}}$.

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