Vapour pressure in mm Hg of 0.1 mole of urea in 180 g of water at 25° C is (The vapour pressure of water at 25°C is 24 mm Hg)

• 2.376

• 20.76

• 23.76

• 24.76

The molar mass of a solute X in g mol^-1, if its 1% solution is isotonic with a 5% solution of cane sugar(molar mass = 342 g mol^-1), is

• 68.4

• 34.2

• 136.2

• 171.2

18 g of glucose is dissolved in 90 g of water. The relative lowering of vapour pressure of the solution is equal to

• 6

• 0.2

• 5.1

• 0.02

The vapour pressure of pure benzene and toluene are 160 and 60 mmHg respectively. The mole fraction of benzene in vapour phase in contact with equimolar solution of benzene and toluene is

• 0.073

• 0.027

• 0.27

• 0.73

115.

6 g of a non-volatile, non-electrolyte X dissolved in 100 gm of water freezes at -0.93°C. The molar mass of X in g mol^-1 is (K_f of H₂O = 1.86 K kg mol^-1).

• 60

• 140

• 180

• 120

The order of basic strength of the following in aqueous solution is

I. C₆H₅NH₂

II. (CH₃)₃N

III. NH₃

IV. CH₃NH₂

V. (CH₃)₂NH

• IV > I > V > III > II

• II > V > IV > III > I

• V > IV > II > III > I

• IV > III > V > II > I

Which one of the following solutions of compounds show highest osmotic pressure?[AB, AB₂,A₂B₃ are ionic compounds]

• 5.0 M urea i= 10 and temperature is 67°C

• 1.5M A₂B₂ type i= 41 temperature is 27°C

• 3.0 M AB type i= 16 and temperature is 27°C

• 2.5 M AB₂ type i = 2.5 and temperature is 57°C.

31g of ethylene glycol (C₂H₆O₂) is dissolved in 600 g of water. The freezing point depression of the solution is (K_f for water is 1.86 K kg mol^-1)

• 0.77 K

• 1.55 K

• 4.65 K

• 3.10 K

One mole of a solute A is dissolved in a given volume of a solvent. The association of the solute takes place according to nA $\rightleftharpoons$ [A]_n. The van't Hoff factor (i) is expressed as:

• i = 1 - x

• i = 1 + $\frac{\mathrm{x}}{\mathrm{n}}$

• i = $\frac{1 - \mathrm{x} + {\displaystyle \frac{\mathrm{x}}{\mathrm{n}}}}{1}$

• i = 1

Freezing point of water is 0°C. At what temperature will one molal solution of NaCl freeze if NaCl is taken to be completely dissociated (molal depression constant of water = 1.86)?

• -3.72°C

• -1.86°C

• 0°C

• 3.72°C