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MHT CET · Chemistry · Solutions

Calculate van't Hoff factor of \(\mathrm{K}_2 \mathrm{SO}_4\) if \(0.1 \mathrm{~m}\) aqueous solution of \(\mathrm{K}_2 \mathrm{SO}_4\) freezes at \(-0.43{ }^{\circ} \mathrm{C}\) and cryoscopic constant of water is \(1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\).

  1. A 2.3
  2. B 2.7
  3. C 3.1
  4. D 3.5
Verified Solution

Answer & Solution

Correct Answer

(A) 2.3

Step-by-step Solution

Detailed explanation

\(\Delta \mathrm{T}_{\mathrm{f}}=\mathrm{i} \mathrm{K} \mathrm{K}_{\mathrm{f}} \mathrm{m} \)
\( \therefore 0.43=\mathrm{i} \times 1.86 \times 0.1 \)
\( \therefore \mathrm{i}=\frac{0.43}{1.86 \times 0.1}=2.3\)
[Note: In the question, the freezing point of aqueous solution is changed from \(-0.43 \mathrm{~K}\) to \(-0.43^{\circ} \mathrm{C}\) to apply appropriate textual concepts.]