02. Lowering of Vapour Pressure
SOLUTIONS

277345 $18 \mathrm{~g}$ of glucose is dissolved in $178.2 \mathrm{~g}$ of water. The vapour pressure of the solution at $100^{\circ} \mathrm{C}$ is (vapour pressure of pure water at $100^{\circ} \mathrm{C}$ is 760 mm Hg.)

1 $767.6 \mathrm{~mm} \mathrm{Hg}$
2 $760 \mathrm{~mm} \mathrm{Hg}$
3 $752.4 \mathrm{~mm} \mathrm{Hg}$
4 $725.4 \mathrm{~mm} \mathrm{Hg}$
5 $745.2 \mathrm{~mm} \mathrm{Hg}$
SOLUTIONS

277342 Assertion : If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., $\mathbf{p}_{\mathbf{s}}>\mathbf{p}^{\circ}$.
Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
SOLUTIONS

277346 The vapour pressure of pure benzene at certain temperature is a 1 bar. A non-volatile, non electrolyte solid weighing $2 \mathrm{~g}$ when added to 39 $\mathrm{g}$ of benzene (molar mass $78 \mathrm{~g} \mathrm{~mol}^{-1}$ ) yields solution of vapour pressure of 0.8 bar, The molar mass of solid substance is

1 32
2 16
3 64
4 48
SOLUTIONS

277347 0.5 molal solution of a solute in benzene shows a depression in freezing point equal to $2 \mathrm{~K}$. Molal depression constant for benzene is $5 \mathrm{~K}$ $\mathrm{kg} \mathrm{mol}^{-1}$. If the solute forms dimer in benzene, what is the $\%$ association?

1 40
2 50
3 60
4 80
SOLUTIONS

277345 $18 \mathrm{~g}$ of glucose is dissolved in $178.2 \mathrm{~g}$ of water. The vapour pressure of the solution at $100^{\circ} \mathrm{C}$ is (vapour pressure of pure water at $100^{\circ} \mathrm{C}$ is 760 mm Hg.)

1 $767.6 \mathrm{~mm} \mathrm{Hg}$
2 $760 \mathrm{~mm} \mathrm{Hg}$
3 $752.4 \mathrm{~mm} \mathrm{Hg}$
4 $725.4 \mathrm{~mm} \mathrm{Hg}$
5 $745.2 \mathrm{~mm} \mathrm{Hg}$
SOLUTIONS

277342 Assertion : If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., $\mathbf{p}_{\mathbf{s}}>\mathbf{p}^{\circ}$.
Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
SOLUTIONS

277346 The vapour pressure of pure benzene at certain temperature is a 1 bar. A non-volatile, non electrolyte solid weighing $2 \mathrm{~g}$ when added to 39 $\mathrm{g}$ of benzene (molar mass $78 \mathrm{~g} \mathrm{~mol}^{-1}$ ) yields solution of vapour pressure of 0.8 bar, The molar mass of solid substance is

1 32
2 16
3 64
4 48
SOLUTIONS

277347 0.5 molal solution of a solute in benzene shows a depression in freezing point equal to $2 \mathrm{~K}$. Molal depression constant for benzene is $5 \mathrm{~K}$ $\mathrm{kg} \mathrm{mol}^{-1}$. If the solute forms dimer in benzene, what is the $\%$ association?

1 40
2 50
3 60
4 80
SOLUTIONS

277345 $18 \mathrm{~g}$ of glucose is dissolved in $178.2 \mathrm{~g}$ of water. The vapour pressure of the solution at $100^{\circ} \mathrm{C}$ is (vapour pressure of pure water at $100^{\circ} \mathrm{C}$ is 760 mm Hg.)

1 $767.6 \mathrm{~mm} \mathrm{Hg}$
2 $760 \mathrm{~mm} \mathrm{Hg}$
3 $752.4 \mathrm{~mm} \mathrm{Hg}$
4 $725.4 \mathrm{~mm} \mathrm{Hg}$
5 $745.2 \mathrm{~mm} \mathrm{Hg}$
SOLUTIONS

277342 Assertion : If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., $\mathbf{p}_{\mathbf{s}}>\mathbf{p}^{\circ}$.
Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
SOLUTIONS

277346 The vapour pressure of pure benzene at certain temperature is a 1 bar. A non-volatile, non electrolyte solid weighing $2 \mathrm{~g}$ when added to 39 $\mathrm{g}$ of benzene (molar mass $78 \mathrm{~g} \mathrm{~mol}^{-1}$ ) yields solution of vapour pressure of 0.8 bar, The molar mass of solid substance is

1 32
2 16
3 64
4 48
SOLUTIONS

277347 0.5 molal solution of a solute in benzene shows a depression in freezing point equal to $2 \mathrm{~K}$. Molal depression constant for benzene is $5 \mathrm{~K}$ $\mathrm{kg} \mathrm{mol}^{-1}$. If the solute forms dimer in benzene, what is the $\%$ association?

1 40
2 50
3 60
4 80
SOLUTIONS

277345 $18 \mathrm{~g}$ of glucose is dissolved in $178.2 \mathrm{~g}$ of water. The vapour pressure of the solution at $100^{\circ} \mathrm{C}$ is (vapour pressure of pure water at $100^{\circ} \mathrm{C}$ is 760 mm Hg.)

1 $767.6 \mathrm{~mm} \mathrm{Hg}$
2 $760 \mathrm{~mm} \mathrm{Hg}$
3 $752.4 \mathrm{~mm} \mathrm{Hg}$
4 $725.4 \mathrm{~mm} \mathrm{Hg}$
5 $745.2 \mathrm{~mm} \mathrm{Hg}$
SOLUTIONS

277342 Assertion : If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., $\mathbf{p}_{\mathbf{s}}>\mathbf{p}^{\circ}$.
Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
SOLUTIONS

277346 The vapour pressure of pure benzene at certain temperature is a 1 bar. A non-volatile, non electrolyte solid weighing $2 \mathrm{~g}$ when added to 39 $\mathrm{g}$ of benzene (molar mass $78 \mathrm{~g} \mathrm{~mol}^{-1}$ ) yields solution of vapour pressure of 0.8 bar, The molar mass of solid substance is

1 32
2 16
3 64
4 48
SOLUTIONS

277347 0.5 molal solution of a solute in benzene shows a depression in freezing point equal to $2 \mathrm{~K}$. Molal depression constant for benzene is $5 \mathrm{~K}$ $\mathrm{kg} \mathrm{mol}^{-1}$. If the solute forms dimer in benzene, what is the $\%$ association?

1 40
2 50
3 60
4 80