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WBJEE · Chemistry · Some Basic Concepts of Chemistry

The mole fraction of ethanol in water is \(0.08\). Its molality is

  1. A \(6.32 \mathrm{~mol} \mathrm{~kg}^{-1}\)
  2. B \(4.83 \mathrm{~mol} \mathrm{~kg}^{-1}\)
  3. C \(3.82 \mathrm{~mol} \mathrm{~kg}^{-1}\)
  4. D \(2.84 \mathrm{~mol} \mathrm{~kg}^{-1}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(4.83 \mathrm{~mol} \mathrm{~kg}^{-1}\)

Step-by-step Solution

Detailed explanation

Hint: \(\begin{aligned} \text { Molality } &=\frac{\mathrm{x}_{\mathrm{EtOH}}}{\mathrm{x}_{\mathrm{H}_{2} \mathrm{O}}} \times \frac{1000}{\mathrm{MW}_{\text {solvent }}} \\ &=\frac{0.08}{0.92} \times \frac{1000}{18} \\ &=4.83 \mathrm{~mol} \mathrm{~kg}^{-1} \end{aligned}\)