# The molal depression constant for water=1.85 deg/molal and for benzene is 5.12 deg/molal. If the ratio of the latent heats of fusion of benzene to water is 3:8, calculate the freezing point of benzene. 1. 6.75$°\mathrm{C}$ 2. 5.12$°\mathrm{C}$ 3. 8.97$°\mathrm{C}$ 4. 6.1$°\mathrm{C}$

Subtopic:  Elevation of Boiling Point |
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Which of the following colligative properties is associated with the concentration term 'molarity'?

1. Lowering of vap.pressure

2. Osmotic pressure

3. Depression in freezing point

4. Elevation in boiling point

Subtopic:  Osmosis & Osmotic Pressure |
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The vapour pressure of a dilute aqueous solution of glucose is 750 mm of Hg at 373 K. The mole fraction of solute in the solution is-
1. 1/10
2. 1/76
3. 1/7.6
4. 1/35

Subtopic:  Relative Lowering of Vapour Pressure |
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Which pair of solutions is likely to exhibit isotonicity at a constant temperature?

1. 0.1 (M) Urea and 0.1 (M) NaCl

2. 0.1 (M) Urea and 0.2 (M) MgCl2

3. 0.1 (M) NaCl and 0.1 (M) Na2SO4

4. 0.1 (M) Ca(NO3)2 and 0.1 (M) Na2SO4

Subtopic:  Osmosis & Osmotic Pressure |
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The latent heat of vapourisation of water is 540 cal g-1 at 100$°\mathrm{C}$. Kb for water is

1. 0.56 K.mole-1

2. 1.86 K.mole-1

3. 0.51 K.mole-1

4. 5.12 K.mole-1

Subtopic:  Elevation of Boiling Point |
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Which of the following aqueous solution has osmotic pressure nearest to that an equimolar solution of K4[Fe(CN)6]?

1. Na2SO4

2. BaCl2

3. Al2(SO4)3

4. C12H22O11

Subtopic:  Osmosis & Osmotic Pressure |
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The molar volume of liquid benzene (density= 0.877 g ml-1) increases by a factor of 2750 as it vapourises at 20$°\mathrm{C}$. At 27$°\mathrm{C}$ when a non-volatile solute (that does not dissociate) is dissolved in 54.6cm3 of benzene, vapour pressure of this solution, is found to be 98.88 mm Hg. calculate the freezing point of the solution.

Given: Enthalpy of vapourisation of benzene(l)=394.57 Jg-1. Enthalpy of fusion of benzene (l) = 10.06 kJ mol-1 Molal depression constant for benzene=5.0 K kg mol-1.

1. 177.65 K

2. 277.65 K

3. 517.65 K

4. 237.15 K

Subtopic:  Depression of Freezing Point |
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The depression in the freezing point of water when 10 g of CH3CH2CHClCOOH is added to 250 g of water is -Ka=1.4 X 10-3, Kf=1.86K kg mol-1

1. 0.15$°\mathrm{C}$

2. 2.15$°\mathrm{C}$

3. 1.15$°\mathrm{C}$

4. 0.65$°\mathrm{C}$

Subtopic:  Depression of Freezing Point |
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The ratio of the vapour pressure of a solution to the vapour pressure of the solvent is

1. Equal to the mole fraction of the solvent

2. Proportional to the mole fraction of the solute

3. Equal to the mole fraction of the solute

4. None of the above

Subtopic:  Relative Lowering of Vapour Pressure |
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Mole fraction of the component A in vapour phase is X1 and mole fraction of component A in liquid mixture is X2 then

(${\mathrm{P}}_{\mathrm{A}}^{0}$ = vapour pressure of pure A; ${\mathrm{P}}_{\mathrm{B}}^{0}$= vapour pressure of pure B),

then total vapour pressure of the liquid mixture is-

1. $\frac{{\mathrm{P}}_{\mathrm{A}}^{0}{\mathrm{X}}_{2}}{{\mathrm{X}}_{1}}$

2. $\frac{{\mathrm{P}}_{\mathrm{A}}^{0}{\mathrm{X}}_{1}}{{\mathrm{X}}_{2}}$

3. $\frac{{\mathrm{P}}_{\mathrm{B}}^{0}{\mathrm{X}}_{1}}{{\mathrm{X}}_{2}}$

4. $\frac{{\mathrm{P}}_{\mathrm{B}}^{0}{\mathrm{X}}_{2}}{{\mathrm{X}}_{1}}$

Subtopic:  Relative Lowering of Vapour Pressure |
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