471.

When helium gas is allowed to expand into vaccum, heating effect is observed. The reason for this is (assume He as a non ideal gas)

• He is an inert gas

• The inversions temperature of helium is very high

• The inversion temperature of helium is very low

• He has the lowest boiling point

Which of the following conditions are correct for real solutions showing negative deviation from Raoult's law?

• ΔH_Mix <0, ΔV_Mix > 0

• ΔH_Mix >0, ΔV_Mix > 0

• ΔH_Mix >0, ΔV_Mix < 0

• ΔH_Mix <0, ΔV_Mix <0

Molal depression constant for a solvent is 4.0 K kg mol^-1. The depression in the freezing point of the solvent for 0.03 mol kg^-1 solution of K₂SO₄ is : (Assume complete dissociation of the electrolyte)

• 0.24 K

• 0.12 K

• 0.18 K

• 0.36 K

For the solution of the gases w, x, y and z in water at 298 K, the Henrys law constants (K_H) are 0.5, 2, 35 and 40 kbar, respectively. The correct plot for the given data is :

The osmotic pressure of a dilute solution of an ionic compound XY in water is four times that of a solution of 0.01 M BaCl₂ in water. Assuming complete dissociation of the given ionic compounds is water, the concentration of XY (in mol L^-1 ) in solution is 

• 4 × 10^-4

• 16 × 10^-4

• 4 × 10^-2

• 6 × 10^-2

At room temperature a dilute solution of urea is prepared by dissolving 0.60g of urea in 360g of water . If the vapour pressure of pure water at this temperature is 35mmHg , Lowering of vapour pressure will be (molar mass of urea =60g mol^-1).

• 0.28mmHg

• 0.031 mmHg

• 0.027Hg

• 0.017mmHg

1 g of a non-volatile non – electrolyte solute is dissolved in 100 g of two different solvents A and B whose ebulliscopic constants are in the ratio of 1:5. The ratio of the elevation in their boiling points, $\frac{∆{\mathrm{T}}_{\mathrm{b}}\left(\mathrm{A}\right)}{∆{\mathrm{T}}_{\mathrm{b}}\left(\mathrm{B}\right)}$ is:

• 1:0.2

• 10: 1

• 5: 1

• 1: 5

A 100⁰C the vapour pressure of a solution of 6.5 g of a solute in 100 g water is 732 mm. If Kb = 0.52, the boiling point of this solution will be

• 100⁰C

• 102⁰C

• 103⁰C

• 103⁰C

Which of the following statements about the composition of the vapour over an ideal 1:1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at 25⁰C.
(Given, vapour pressure data at 25⁰C benzene = 12.8 kPa, toluene = 3.85 kPa)

• The vapour will contain a higher percentage of toluene

• The vapour will contain equal amounts of benzene and toluene

• Not enough information is given to make a prediction

• Not enough information is given to make a prediction

which is one not equal to zero for an ideal solution?

• ΔH_mix
• ΔS_mix
• ΔV_mix
• ΔV_mix