The vapour density of undecomposed N2O4 is 46. When heated, vapour density decreases to 24.5 due to its dissociation to NO2. The percent dissociation of N2O4 at the final temperature is:

(a) 87                                         (b) 60

(c) 40                                         (d) 70

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At 298 K, 500cm3 H2O dissolved 15.30 cm3 CH4(STP) under a partial pressure of methane of one atm. If Henery's law holds, what pressure is required to cause 0.001 mole methane to dissolve in 300cm3 water ?

(a) 0.286 atm

(b) 2.486 atm

(c) 1.286 atm

(d) 3.111 atm

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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.

(a) 5.75$°\mathrm{C}$

(b) 5.12$°\mathrm{C}$

(c) 4.97$°\mathrm{C}$

(d) 6.1$°\mathrm{C}$

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Which of the following colligative properties is associated with the concentration term 'molarity'?

(a) Lowering of vap.pressure

(b) Osmotic pressure

(c) Depression in freezing point

(d) Elevation in boiling point

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The Ksp (25$°\mathrm{C}$) of sparingly soluble salt XY2(s) is 3.56X10-5(mol lit-1)3 and at 30$°\mathrm{C}$ the vapour pressure of its saturated solution in water is 31.78 mm Hg. Calculate the enthalpy change of the reaction.

Given: Vapour pressure of pure water=31.82 mm Hg

(a) 42.5 kJ/mol.

(b) 32.1 kJ/mol.

(c) 24.5 kJ/mol.

(d) 52.5 kJ/mol.

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The vapoure pressure of a dilute aqueous solution of glucose is 750mm of mercury at 373K. The mole fraction of solute in the solution is-

(a) 1/10

(b) 1/76

(c) 1/7.6

(d) 1/35

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Which one of the folowing pairs of solution can we expect to be isotonic at the same temperature-

(a) 0.1 (M) urea and 0.1 (M) NaCl

(b) 0.1 (M) urea and 0.2 (M) MgCl2

(c) 0.1 (M) NaCl and 0.1 (M) Na2SO4

(d) 0.1 (M) Ca(NO3)2 and 0.1 (M) Na2SO4

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The latent heat of vapourisation of water is 540 cal g-1 at 100$°\mathrm{C}$. Kb for water is

(a) 0.562 K.mole-1

(b) 1.86 K.mole-1

(c) 0.515 K.mole-1

(d) 5.12 K.mole-1

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Which of the following aqueous solution has osmotic pressure nearest to that an equimolar solution of K4[Fe(CN)6]?

(a) Na2SO4

(b) BaCl2

(c) Al2(SO4)3

(d) C12H22O11

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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.

(a) 177.65 K

(b) 277.65 K

(c) 517.65 K

(d) 237.15 K