Verified Solution • 2025–26 Session moderate

QJEEM25Ch0217: JEE Main 2025 Chemistry - Class 12 JEEM25Ch0217 Solution: When a non-volatile solute is added to the solvent, the vapour…

When a non-volatile solute is added to the solvent, the vapour pressure of the solvent decreases by 10 mm of Hg . The mole fraction of the solute in the solution is 0.2 . What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg ?

Multiple Choice Options

  • A 0.2
  • B 0.4
  • C 0.8
  • D 0.6

Step-by-Step Verified Solution

amp;∵P∘−P∝Xsolute amp; and ∵10∝0.2amp;∴20∝0.4amp;∴Xsolvent =1−Xsolute amp;=1−0.4amp;=0.6\begin{aligned}& \because \mathrm{P}^{\circ}-\mathrm{P} \propto \mathrm{X}_{\text {solute }} \\& \text { and } \because 10 \propto 0.2 \\& \therefore 20 \propto 0.4 \\& \therefore \mathrm{X}_{\text {solvent }}=1-\mathrm{X}_{\text {solute }} \\& \quad=1-0.4 \\& \quad=0.6\end{aligned}

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