1
MCQ (Single Correct Answer)

NEET 2016 Phase 2

Which one of the following is incorrect for ideal solution?
A
$$\Delta {H_{mix}} = 0$$
B
$$\Delta {U_{mix}} = 0$$
C
$$\Delta P = {P_{obs}} - P$$calculated by Raoult's law
D
$$\Delta {G_{mix}} = 0$$

Explanation

For ideal solution, we have

$$\Delta $$Hmix = 0, $$\Delta $$Vmix = 0

Now Umix = ∆Hmix – P$$\Delta $$Vmix

$$ \therefore $$ $$\Delta $$Umix = 0

Also, for an ideal solution,

pA = xApAo, pB = xBpBo

$$ \therefore $$ $$\Delta $$p = pobserved – pcalculated = 0

$$\Delta $$Gmix = $$\Delta $$Hmix – T$$\Delta $$Smix

For an ideal solution, $$\Delta $$Smix $$ \ne $$ 0

$$ \therefore $$ $$\Delta $$Gmix $$ \ne $$ 0
2
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
3
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.
4
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

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