Verified Solution • 2025–26 Session moderate

QJEEM09Chaa4e: JEE Main 2009 Chemistry - Class 12 JEEM09Chaa4e Solution: Two liquids X and Y form an ideal solution. At 300K, vapour…

Two liquids X and Y form an ideal solution. At 300K, vapour pressure of the solution containing 1 mol of X and 3 mol of Y is 550 mm Hg. At the same temperature, if 1 mol of Y is further added to this solution, vapour pressure of the solution increases by 10 mm Hg. Vapour pressure (in mm Hg) of X and Y in their pure states will be, respectively :

Multiple Choice Options

  • A 200 and 300
  • B 300 and 400
  • C 400 and 600
  • D 500 and 600

Step-by-Step Verified Solution

Ptotal=PA∘XA+PB∘XB;{P_{total}} = P_A^ \circ {X_A} + P_B^ \circ {X_B};

        \,\,\,\,\,\,\,\, 550=PA∘×14+PB∘×34550 = P_A^ \circ \times {1 \over 4} + P_B^ \circ \times {3 \over 4}

PA∘+3PB∘=550×4  ...(i)P_A^ \circ + 3P_B^ \circ = 550 \times 4\,\,...\left( i \right)

In second case

Ptotal=PA∘×15+PB∘×45{P_{total}} = P_A^ \circ \times {1 \over 5} + P_B^ \circ \times {4 \over 5}

PA∘+4PB∘=560×5  ...(ii)P_A^ \circ + 4P_B^ \circ = 560 \times 5\,\,...\left( {ii} \right)

Subtract (i)(i) from (ii)(ii)

∴\therefore         \,\,\,\,\,\,\,\, PB∘=560×5−550×4=600P_B^ \circ = 560 \times 5 - 550 \times 4 = 600

As         \,\,\,\,\,\,\,\, PA∘=400P_A^ \circ = 400

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