Solutions

Which of the following units is useful in relating concentration of solution

with its vapour pressure?

• Mole fraction

• Parts per million

• Mass percentage

• Molarity

A beaker contains a solution of substance ‘A’. Precipitation of substance ‘A’

takes place when small amount of ‘A’ is added to the solution. The solution is

_________.

• Saturated

• Unsaturated

• Supersaturated

• Concentrated

Answer explanation

If added substance dissolves, the solution is unsaturated. If it

does not dissolve solution is saturated. If precipitation occurs solution

is supersaturated.

Assertion : When NaCl is added to water a depression in freezing point is

observed.

Reason : The lowering of vapour pressure of a solution causes

depression in the freezing point.

• Both A & R are true and R is correct explanation of A

• Both A & R are true but R is not correct explanation of A

• A true, R false

• A false, R true

If two liquids A and B form minimum boiling azeotrope at some specific

composition then _______________.

• A–B interactions are stronger than those between A–A or B–B.

• vapour pressure of solution increases because more number of

  molecules of liquids A and B can escape from the solution.

• vapour pressure of solution decreases because less number of

  molecules of only one of the liquids escape from the solution.

• A–B interactions are weaker than those between A–A or B–B

We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with

concentrations 0.1M, 0.01M and 0.001M, respectively. The value of van’t Hoff

factor for these solutions will be in the order______.

• iA > iB > iC

• iA < iB > iC

• iA = iB = iC

• iA < iB < iC

The value of Henry’s constant KH

is _____________.

• greater for gases with higher solubility.

• greater for gases with lower solubility.

• Constant for all gases

• Not related to solubility of gases

In comparison to a 0.01 M solution of glucose, the depression in freezing point

of a 0.01 M MgCl2

solution is _____________.

• the same

• about twice

• about three times

• about six times

Low concentration of oxygen in the blood and tissues of people living at high

altitude is due to ____________.

(i) low temperature

(ii) low atmospheric pressure

(iii) high atmospheric pressure

(iv) both low temperature and high atmospheric pressure

• Low temperature

• Low atmospheric pressure

• High atmospheric pressure

• Both low temperature and high atmospheric pressure

Intermolecular forces between two benzene molecules are nearly of same

strength as those between two toluene molecules. For a mixture of benzene

and toluene, which of the following are not true?

• ∆mix H = zero

• ∆mix V = zero

• These will form minimum boiling azeotrope.

• These will not form ideal solution

Which of the following aqueous solutions should have the highest boiling point?

• 1.0 M NaOH

• 1.0 M Na2SO4

• 1.0 M NH4NO3

• 1.0 M KNO3