1 molal aqueous solution of an electrolyte A2B3 is 60% ionised. The boiling point of the solution at 1 atm is-. (Rounded-off to the nearest integer)
[Given Kb for (H2O) = 0.52 K kg mol–1]

1. 373 K 2. 380 K
3. 375 K 4. 377 K
Subtopic:  Van’t Hoff Factor |
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When 12.2 g of benzoic acid is dissolved in 100 g of water, the freezing point of the solution was found to be
–0.93 °C. The number (n) of benzoic acid molecules associated (assuming 100% association) is:
(Kf(H2O) = 1.86K kg mol–1)

1. 3 2. 1
3. 2 4. 5

Subtopic:  Van’t Hoff Factor |
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When 9.45 g of ClCH2COOH is added to 500 mL of water, its freezing point drops by 0.5 ºC.
The dissociation constant of ClCH2 COOH is x × 10–3. The value of x is:

(Rounded off to the nearest integer)

[Kf(H2O)=1.86 kgmol1]

1. 36 × 10-3 
2. 29 × 10-3 
3. 45 × 10-3 
4. 30 × 10-3 

Subtopic:  Van’t Hoff Factor |
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Molal depression constant for a solvent is 4.0 K kg mol–1 . The depression in the freezing point of the solvent for 0.03 mol kg–1 solution of K2SO4 is : (Assume complete dissociation of the electrolyte)

1. 0.36 K
2. 0.18 K
3. 0.12 K
4. 0.24 K

Subtopic:  Depression of Freezing Point | Van’t Hoff Factor |
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The degree of dissociation α of a weak electrolyte, AxBy is related to van't Hoff factor (i) by the expression :

1. α=i1(x+y1)

2. α=i1x+y+1

3. α=x+y1i1

4. α=x+y+1i1

Subtopic:  Van’t Hoff Factor |
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If the freezing point of 0.5 w/w % KCl (aq) solution is - 0.24°C.
The percentage of dissociation of KCl in the solution is: 
[Kf=1.86 K-kg/mol]

1. 99 %
2. 67 %
3. 79 %
4. 91 %
Subtopic:  Van’t Hoff Factor |
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Consider the two statements:
Statement I:  At 20 °C, the molality of KCl solution is 'X' m, and on decreasing temperature to -10 °C molality remains unchanged.
Statement II:  On changing temperature mass remains unchanged.
 
1.  Both Statement I and Statement II are True.
2. Both Statement I and Statement II are False.
3.  Statement I is True, and Statement II is False.
4.  Statement I is False, and Statement II is True.
Subtopic:  Elevation of Boiling Point | Van’t Hoff Factor |
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Which of the following has more relative lowering in vapour pressure at the same temperature
1. 0.1 M urea
2. 0.1 M NaCl
3. 0.1 M sucrose
4. 0.1 M CaCl2
Subtopic:  Relative Lowering of Vapour Pressure | Van’t Hoff Factor |
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Consider the given dissociation reaction
\(\mathrm{HX}_{(\mathrm{aq})} \rightleftharpoons \mathrm{H}_{(\mathrm{aq})}^{+}+\mathrm{X}_{(\mathrm{aq})}^{-} \)
with an acid dissociation constant (\(K_a\)) of \(1.2 \times 10^{-5}\). What is the osmotic pressure (in atm) of a 0.03 M HX solution at 300 K?
1. 4 atm 2. 2 atm
3. 1 atm 4. 6 atm
Subtopic:  Osmosis & Osmotic Pressure | Van’t Hoff Factor |
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For the compound MX2, the observed mass is 65.6, while the normal mass is 164. The percentage degree of ionization of MX2 (rounded to the nearest integer) is:
1. 75
2. 60
3. 50
4. 85
Subtopic:  Van’t Hoff Factor |
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