1
MCQ (Single Correct Answer)

AIPMT 2015 Cancelled Paper

Which one of the following electrolytes has the same value of van't Hoff factor (i) as that of Al2(SO4)3 (if all are 100% ionised)?
A
Al(NO3)3
B
K4[Fe(CN)6]
C
K2SO4
D
K3[Fe(CN)6]

Explanation

Ai2(SO4)3 ⇌ 2Al+3 + 3SO42–

van't Hoff factor, i = 5

K2SO4 ⇌ 2K+ + SO42–

van't Hoff factor, i = 3

K3[Fe(CN)6] ⇌ 3K+ + [Fe(CN)6]2-

van't Hoff factor, i = 4

Al(NO3)3 ⇌ Al3+ + 3NO3

van't Hoff factor, i = 4

K4[Fe(CN)6] ⇌ 4K+ + [Fe(CN)6]4–

van't Hoff factor, i = 5
2
MCQ (Single Correct Answer)

AIPMT 2015 Cancelled Paper

Which of them is not equal to zero for an ideal solution?
A
$$\Delta {V_{mix}}$$
B
$$\Delta P = {P_{observed}} - {P_{Raoult}}$$
C
$$\Delta {H_{mix}}$$
D
$$\Delta {S_{mix}}$$

Explanation

For an ideal solution, $$\Delta $$Smix > 0 while $$\Delta $$Hmix, $$\Delta $$Vmix and $$\Delta $$P all are 0.
3
MCQ (Single Correct Answer)

AIPMT 2015

What is the mole fraction of the solute in a 1.00 m aqueous solution?
A
1.770
B
0.0354
C
0.0177
D
0.177

Explanation

Number of moles of water in 1000 g = $${{1000} \over {18}}$$ = 55.56 mol

Thus, mole fraction of solute = $${1 \over {1 + 55.56}}$$ = 0.0177
4
MCQ (Single Correct Answer)

AIPMT 2015 Cancelled Paper

The boiling point of 0.2 mol kg$$-$$1 solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case?
A
Molecular mass of X is less than the molecular mass of Y.
B
Y is undergoing dissociation in water while X undergoes no change.
C
X is indergoing dissociation in water.
D
Molecular mass of X is greater than the molecular mass of Y.

Explanation

$$\Delta $$Tb = iKbm

Given, ($$\Delta $$Tb)x > ($$\Delta $$Tb)y

$$ \therefore $$ ixKbm > iyKbm

$$ \Rightarrow $$ ix > iy

(Kb is same for same solvent)

So, x is undergoing dissociation in water.

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