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MHT CET · Chemistry · Solutions

The vapour pressure of a solvent decrease by \(2.5 \mathrm{~mm} \mathrm{Hg}\) by adding a solute. What is the mole fraction of solute? (Vapour pressure of pure solvent is \(250 \mathrm{~mm} \mathrm{Hg}\) )

  1. A \(0.88\)
  2. B \(0.01\)
  3. C \(0.1\)
  4. D \(0.99\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(0.01\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \frac{\mathrm{P}^{\circ}-\mathrm{P}_{\mathrm{S}}}{\mathrm{P}^0}=\mathrm{X}_{\text {solute }} \\ & \mathrm{P}^{\circ}-\mathrm{P}_{\mathrm{S}}=2.5 \mathrm{~mm}, \mathrm{P}^{\circ}=250 \mathrm{~mm} \\ & \frac{2.5}{250}=\mathrm{X}_{\text {solute }} \\ & \mathrm{X}_{\text {solute }}=0.01\end{aligned}\)