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The vapour pressures of two liquids 'P' and 'Q' are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mole of Q would be :-
A
68 torr
B
140 torr
C
72 torr
D
20 torr
Detailed Solution
By Raoult's law, for an ideal solution: $P_{total} = x_P P_P^\circ + x_Q P_Q^\circ$
Total moles $= 3 + 2 = 5$
$x_P = \dfrac{3}{5} = 0.6$ and $x_Q = \dfrac{2}{5} = 0.4$
$P_{total} = 0.6 \times 80 + 0.4 \times 60$
$= 48 + 24$
$= 72$ torr
Total moles $= 3 + 2 = 5$
$x_P = \dfrac{3}{5} = 0.6$ and $x_Q = \dfrac{2}{5} = 0.4$
$P_{total} = 0.6 \times 80 + 0.4 \times 60$
$= 48 + 24$
$= 72$ torr