In countries nearer to polar region, the roads are sprinkled with CaCl₂ .This is :

• to minimise the wear and tear of the roads

• to minimise the snow fall

• to minimise pollution

• to minimise the accumulation of dust on the road

The solubility of a gas in water at 300 K under a pressure of 100 atm is 4 x 10^-3 kg L^-1. Therefore, the mass of the gas in kg dissolved 250 mL of water under a pressure of 250 atm at 300 K is :

• 2.5 x 10^-3

• 2.0 x 10^-3

• 1.25 x 10^-3

• 5.0 x 10^-3

The depression in freezing point of 0.1 M aqueous solutions of HCl, CuSO₄ and K₂SO₄ are in the ratio

• 1 : 1 : 1.5

• 1 : 2 : 3

• 1 : 1 : 1

• 2 : 4 : 3

Which of the following pairs of substances cannot exist together in solution?

• Na₂CO₃ + NaOH

• NaHCO₃ + Na₂CO₃

• NaHCO₃ + NaOH

• NaOH + HCl

545.

Assertion : Azeotropic mixtures are formed only by non-ideal solutions and they may have boiling points either greater than both the components or lesser than both the components.

Reason : The composition of the vapour phase is same as that ofthe liquid phase of an azeotropic mixture.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false

• If both assertion and reason are false.

Large difference in boiling points is observed in

• N and P

• P and As

• As and Sb

• Sb and Bi

Arrange the given compounds in decreasing order of boiling points.

I. CH₃CH₂CH₂CH₂Br

II. C(CH₃)₃Br

III. CH₃-CH₂-CH(CH₃)-Br

• I > III > II

• II > I > III

• I > II > III

• III > I > II

Two elements A and B form compounds of formula AB₂ and AB₄. When dissolved in 20.0 g of benzene 1.0 g of AB₂ lowers freezing point by 2.3°C whereas 1.0 g of AB₄ lowers freezing point by 1.3°C. The K_f for benzene is 5.1. The atomic masses of A and B are

• 25, 42

• 42, 25

• 52, 48

• 48, 52

The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45°C. The degree of association of acetic acid in benzene is (Assume acetic acid dimerises in benzene and K_f for benzene = 5.12K kg mol^-1) M_observed of acetic acid =  113.78

• 94.5%

• 54.9%

• 78.2%

• 100%

60 g of urea is dissolved in 1100 g solution. To keep $∆$Tf/Kf as 1 mol kg-1 water separated in the form of ice is :

• 40 g

• 60 g

• 100 g

• 200 g