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1.Solution and Colligative properties
medium
A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of $290 \,mm$ at $300\, K.$ The vapour pressure of propyl alcohol is $200\, mm.$ If the mole fraction of ethyl alcohol is $0.6,$ its vapour pressure ( in $mm$) at the same temperature will be
A
$360$
B
$350$
C
$300$
D
$700$
(AIEEE-2007)
Solution
$P_{B}^{\circ}=200\,\mathrm{mm}, x_{A}=0.6$
$x_{B}=1-0.6=0.4, P=290$
$P=P_{A}+P_{B}=P_{A}^{\circ} x_{A}+P_{B}^{\circ} x_{B}$
$\Rightarrow 290=P_{A}^{\circ} \times 0.6+200 \times 0.4$
$\therefore \quad P_{A}^{\circ}=350 \,\mathrm{mm}$
Standard 12
Chemistry
