HARD
JEE Main
IMPORTANT
Earn 100

The vapour pressure of a 0.01 m solution of a weak base BOH in water at 20°C is 17.536 mm. Calculate Kb for the base. Aqueous tension at 20°C=17.54 mm. (Give answer as Kb × 104 )

[Hint i= observed lowering in vapour pressure calculated lowering in vapour pressure =p-pobs. p0·nN=17.540-17.53617.54×0.011000/18,

Then apply i=1+x and Kb=0.01x21-x]

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Important Questions on Dilute Solution and Colligative Properties

HARD
JEE Main
IMPORTANT

In an Ostwald-Walker experiment, dry air was first blown through a solution containing a certain amount of solute (M=278) in 150 g of water and then also through pure water. The loss in mass of water was found to be 0.0827 g, while the mass of water absorbed in sulphuric acid was 3.317 g. Calculate the amount of the solute.

Give your answer up to two decimal places without rounding-off.

HARD
JEE Main
IMPORTANT
Pheromones are compounds secreted by the females of many insect species to attract males. One of these compounds contains 80.78% C,13.56% H, and 5.66% O. A solution of 1.0 g of this substance in 8.50 cc of benzene freezes at 3.37°C What is the molecular weight and the molecular formula of the compound? (f.p. of  C6H6=5.5°C, Kf C6H6=5·12° C/m)
MEDIUM
JEE Main
IMPORTANT

The vapour pressure of pure water at 25°C is 23.62 mm Hg, What will be the vapour pressure of a solution of 1.5 g of urea in 50 g of water?

Give your answer up to two decimal places.

EASY
JEE Main
IMPORTANT
A molal solution is one that contains one mole of a solute in which of the following?
EASY
JEE Main
IMPORTANT
Vapour pressure of a solvent is 17.5 mm Hg while that of its dilute solution is 17.45. What will be the mole fraction of the solvent?
EASY
JEE Main
IMPORTANT
Which of the following is not a colligative property?
EASY
JEE Main
IMPORTANT
When an ideal binary solution is in equilibrium with its vapour, the molar ratio of the two components in the solution and in the vapour phases will be:
EASY
JEE Main
IMPORTANT

The osmotic pressure of a solution is given by which of the following relation?

(c is the concentration in moles litre-1)