Osmotic pressure observed when benzoic acid is dissolved in benzene is less than that expected from theoretical considerations .This is because :

• benzoic acid is an organic solute

• benzoic acid has higher molar mass than benzene

• benzoic acid gets associated in benzene

• benzoic acid gets dissociated in benzene

For a dilute solution, Raoult's law states that

• the relative lowering of vapour pressure is proportional to the amount of solute in solution

• the relative lowering of vapour pressure is equal to the mole fraction of solute

• the lowering of vapour pressure is equal to the mole fraction of the solute

• the vapour pressure of the solution is equal to the mole fraction of the solvent.

To a 25 mL H₂O₂ solution, excess of acidified solution of Kl was added. The iodine liberated required 20 ml of 0.3 N Na₂S₂O₃ solution. The volume strength of H₂O₂ solution is

• 1.344 g/L

• 3.244 g/L

• 5.4 g/L

• 4.08 g/L

A 0.1 molal solution of an acid is 4.5% ionized. Calculate freezing point. (molecular weight of the acid is 300). K_f = 1.86 K mol^-1 kg.

• -0.194$°$C

• 2.00$°$C

• 0$°$C

• -0.269$°$C

A mixture of two miscible liquids A and B is distilled under equilibrium conditions at 1 atm pressure. The mole fraction of A in solution and vapour phase are 0.30 and 0.60 respectively. Assuming ideal behaviour of the solution and the vapour, calculate the ratio of the vapour pressure of pure A to that of pure B.

• 4.0

• 3.5

• 2.5

• 1.85

576.

1 mol each of the following compounds is dissolved in 1L of solution. Which will have the largest $∆{\mathrm{T}}_{\mathrm{b}}$ value?

• HF

• HCl

• HBr

• HI

If two substances A and B have ${\mathrm{P}}_{\mathrm{A}}^{°}$ : ${\mathrm{P}}_{\mathrm{B}}^{°}$ = 1 : 2 and have mole fraction in solution 1 : 2 then mole fraction of A in vapours :

• 0.33

• 0.25

• 0.52

• 0.2

If an aqueous solution of glucose is allowed to freeze then crystal of which will be separated out first ?

• Glucose

• Water

• Both (a) and (b)

• None of these

The root mean square speed of the molecules of diatomic gas is u. When the temperature is doubled, the molecules dissociate into two atoms. The new rms speed of the atom is

• $\sqrt{2\mathrm{u}}$

• u

• 2u

• 4u

Assertion : When a concentrated solution is diluted by adding more water, molarity of the solution remains unchanged.

Reason : Product of moles of a solute and volume is equal to the molarity.

• 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.