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.

Normal solution is :

• inert solution

• acidic solution

• one litre containing one equivalent

• basic solution

The vapour pressure will be lowest for :

• 0.1 M sugar solution

• 0.1 M KCl solution

• 0.1 M Cu(NO₃)₂ solution

• 0.1 M AgNO₃ solution

Blood cells will remain as such in :

• hypertonic solution

• hypotonic solution

• isotonic solution

• none of the above

308.

A 5% solution (by mass) of cane sugar in water has freezing point of 271 K and freezing point of, pure water is 273.15 K. The freezing point of a 5% solution (by mass) of glucose in water is

• 271 K

• 273.15 K

• 269.07 K

• 277.23 K.

Assertion : If red blood cells were removed from the body and placed in pure water, pressure inside the cells increases.

Reason : The concentration of salt content in the cells increases.

• If both assertion and reason are true and reason is the correct explanation of the assertion.

• If both assertion and reason are true but reason is not the correct explanation of the assertion

• If assertion is true, but reason is false.

• Both assertion and reason are false statements.

Assertion : The water pouch of instant cold pack for treating athletic injuries breaks when squeezed and NH₄NO₃ dissolves lowering the temperature.

Reason : Addition of non-volatile solute into solvent results into depression of freezing point of solvent.

• If both assertion and reason are true and reason is the correct explanation of the assertion.

• If both assertion and reason are true but reason is not the correct explanation of the assertion.

• If assertion is true, but reason is false.

• Both assertion and reason are false statements.