Which of the following aqueous solution has minimum freezing point ?

0.01 m NaCl
0.005 m C₂H₅OH
0.005 m MgI₂
0.005 m MgSO₄

Solution

Azeotropic mixture of water and HCl has the percentage of HCl.

20.2%
26.4%
48%
68%

Solution

Liquid mixture having a definite composition and boil like a pure liquid is called an azeotrope.
⇒ Mixture showing +ive deviation from Raoult's Law forms minimum boiling azeotrope while mixture showing –ive deviation from Raoult's law forms maximum boiling azeotrope.

A solution of acetone in ethanol

shows a positivedeviation from Raoult’s law
behaves like a non ideal solution
obeys Raoult’s law
shows a negative deviation from Raoult’s law

Solution

A solution of acetone in ethanol shows positive deviation from Raoult's law.It is because ethanol molecules are strongly hydrogen bonded. When acetone is added, these molecules break the hydrogen bonds and ethanol becomes more volatile.Therefore its vapour pressure is increased.

The vapour pressure of a solvent decreases by 10 mm of Hg when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of Hg?

Solution

When a hard boiled egg after shelling is immersed in saturated brine:

it shrinks
it grows is size
its size remains unchanged
it initially grows in size and then shrinks

Solution

When hard boiled egg after shelling is immersed in saturated brine, its size remains same because of the cagulation of inner liquid there is no flow of solvent molecules across the membrane.

The vapour pressure at a given temperature of an ideal solution containing 0.2 mol of a non-volatile solute and 0.8 mol of solvent is 60 mm of Hg. The vapour pressure of the pure solvent at the same temperature is

150 mm of Hg
60 mm of Hg
75 mm of Hg
120 mm of Hg

Solution

Which will form maximum boiling point azeotrope

HNO₃ + H₂O solution
C₂H₅OH + H₂O solution
C₆H₆ + C₆H₅CH₃ solution
None of these

Solution

The molar freezing point constant for water is 1.86 °C/mol. If 342 g of cane sugar (C₁₂H₂₂O₁₁) is dissolved in 1000 g of water, the solution will freeze at :

– 1.86°C
1.86°C
– 3.92°C
2.42°C

Solution

The azeotropic mixture of water (b.p.100°C) and HCl(b.p.85°C) boils at 108.5°C. When this mixture is distilled it is possible to obtain

pure HCl
pure water
pure water as well as pure HCl
neither HCl nor H₂O in their pure states

Solution

Azeotropic mixture is constant boiling mixture, it is not possible to separate the components of azeotropic mixture by boiling.

The molal elevation constant is the ratio of elevation in boiling point to:

molality
mole fraction
molarity
none

Solution

Molal elevation constant is given by the formula,
K_b = ΔT_b / m , where m is molality and ΔT_b is elevation in boiling point.

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