NEW
New Website Launch
Experience the best way to solve previous year questions with mock tests (very detailed analysis), bookmark your favourite questions, practice etc...
1

AIPMT 2011 Prelims

MCQ (Single Correct Answer)
The van't Hoff factor $$i$$ for a compound which undergoes dissociation in one solvent and association in other solvent is respectively
A
less than one and greater than one
B
less than one and less than one
C
greater than one and less than one
D
greater than one and greater than one.

Explanation

From the value of van’t Hoff factor i it is possible to determine the degree of dissociation or association. In case of dissociation, i is greater than 1 and in case of association i is less than 1.
2

AIPMT 2011 Mains

MCQ (Single Correct Answer)
200 mL of an aqueous solution of a protein contains its 1.26 g. The osmotic pressure of this solution at 300 K is found to be 2.57 $$ \times $$ 10$$-$$3 bar. The molar mass of protein will be (R = 0.083 L bar mol$$-$$1 K$$-$$1)
A
51022 g mol$$-$$1
B
122044 g mol$$-$$1
C
31011 g mol$$-$$1
D
61038 g mol$$-$$1

Explanation

Osmotic pressure, $$\pi $$ = CRT

$$ \Rightarrow $$ $$\pi $$ = $${n \over V}$$RT

$$ \Rightarrow $$ $$\pi $$V = $${w \over M}$$RT

M = $${{wRT} \over {\pi V}}$$

= $${{1.26 \times 0.083 \times 300} \over {2.57 \times {{10}^{ - 3}} \times {{200} \over {1000}}}}$$

= $${{1.26 \times 0.083 \times 300} \over {2.57 \times {{10}^{ - 3}} \times 0.2}}$$

= 61038 g mol–1
3

AIPMT 2010 Prelims

MCQ (Single Correct Answer)
An aqueous solution is 1.00 molal in KI. Which change will cause the vapour pressure of the solution to increase?
A
Addition of NaCl
B
Addition of Na2SO4
C
Addition of 1.00 molal KI
D
Addition of water

Explanation

Addition of solute decreases the vapour pressure as some sites of the surface are occupied by solute particles resulting in decreased surface area. However, addition of solvent, i.e., dilution increases the surface area of the liquid surface, thus results in increased vapour pressure. Hence, addition of water to the aqueous solution of (1 molal) KI results in increased vapour pressure.
4

AIPMT 2010 Prelims

MCQ (Single Correct Answer)
A solution of sucrose (molar mass = 342 g mol$$-$$) has been prepared by dissolving 68.5 g of sucrose in 1000 g of water. The freezing point of the solution obtained will be (Kf for water = 1.86 K kg mol$$-$$1)
A
$$-$$ 0.372oC
B
$$-$$ 0.520oC
C
+ 0.372oC
D
$$-$$ 0.570oC

Explanation

Depression in freezing point,

$$\Delta $$Tf = Kf $$ \times $$ m

m = $${{{w_B}} \over {{M_B}}} \times {{1000} \over {{W_A}}}$$

= $${{68.5 \times 1000} \over {342 \times 1000}}$$

$$\Delta $$Tf = 1.86 $$ \times $$ $${{68.5} \over {342}}$$

= 0.372 oC

$$ \therefore $$ Tf = 0 - 0.372 oC = - 0.372 oC

Joint Entrance Examination

JEE Main JEE Advanced WB JEE

Graduate Aptitude Test in Engineering

GATE CSE GATE ECE GATE EE GATE ME GATE CE GATE PI GATE IN

Medical

NEET

CBSE

Class 12