(D) Given: Mole ratio $n_A : n_B = 1 : 4$. Therefore,mole fractions are $X_A = 1/5 = 0.2$ and $X_B = 4/5 = 0.8$.Pure vapor pressures: $P_A^0 = 440 \ m

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(D) Given: Mole ratio $n_A : n_B = 1 : 4$. Therefore,mole fractions are $X_A = 1/5 = 0.2$ and $X_B = 4/5 = 0.8$.Pure vapor pressures: $P_A^0 = 440 \ mm$,$P_B^0 = 120 \ mm$.Total pressure $P_{total} = P_A^0 X_A + P_B^0 X_B = (440 \times 0.2) + (120 \times 0.8) = 88 + 96 = 184 \ mm$.According to Dalton's Law,the mole fraction in the vapor phase $Y_A = P_A / P_{total}$.$P_A = P_A^0 X_A = 440 \times 0.2 = 88 \ mm$.$Y_A = 88 / 184 \approx 0.478$.

Class 12 Chemistry Solutions Lowering of vapour pressure

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In a solution,the mole ratio of pentane $(A)$ and hexane $(B)$ is $1:4$. At $20^o C$,the vapor pressures of these pure hydrocarbons are $440 \ mm$ and $120 \ mm$ respectively. The mole fraction of pentane in the vapor phase is.....

A
$0.549$
B
$0.2$
C
$0.786$
D
$0.478$

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Lowering of vapour pressure

Among the following substances,the lowest vapour pressure is exerted by

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In a binary solution of $A$ and $B$,the vapor pressure of pure $A$ is less than the vapor pressure of pure $B$. If $X_A$ is the mole fraction of $A$ in the liquid phase and $Y_A$ is the mole fraction of $A$ in the vapor phase,then ..........

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The vapour pressure of water at $20\, ^oC$ is $17.5\, mm\, Hg$. If $18\, g$ of glucose $(C_6H_{12}O_6)$ is added to $178.2\, g$ of water at $20\, ^oC$,the vapour pressure of the resulting solution will be .......... $mm\, Hg$.

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When $25 \ g$ of a non-volatile solute is dissolved in $100 \ g$ of water, the vapour pressure is lowered by $2.25 \times 10^{-1} \ mm$. If the vapour pressure of water at $20^{\circ}C$ is $17.5 \ mm$, what is the molecular weight of the solute?

DifficultAP EAMCET 2008

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The ratio of loss in weight of solvent to gain in weight of $CaCl_{2}$ tube in Ostwald-Walker method is:

MediumMHT CET 2010

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In a solution,the mole ratio of pentane $(A)$ and hexane $(B)$ is $1:4$. At $20^o C$,the vapor pressures of these pure hydrocarbons are $440 \ mm$ and $120 \ mm$ respectively. The mole fraction of pentane in the vapor phase is.....

Similar Questions

Among the following substances,the lowest vapour pressure is exerted by

In a binary solution of $A$ and $B$,the vapor pressure of pure $A$ is less than the vapor pressure of pure $B$. If $X_A$ is the mole fraction of $A$ in the liquid phase and $Y_A$ is the mole fraction of $A$ in the vapor phase,then ..........

The vapour pressure of water at $20\, ^oC$ is $17.5\, mm\, Hg$. If $18\, g$ of glucose $(C_6H_{12}O_6)$ is added to $178.2\, g$ of water at $20\, ^oC$,the vapour pressure of the resulting solution will be .......... $mm\, Hg$.

When $25 \ g$ of a non-volatile solute is dissolved in $100 \ g$ of water, the vapour pressure is lowered by $2.25 \times 10^{-1} \ mm$. If the vapour pressure of water at $20^{\circ}C$ is $17.5 \ mm$, what is the molecular weight of the solute?

The ratio of loss in weight of solvent to gain in weight of $CaCl_{2}$ tube in Ostwald-Walker method is:

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