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JEE Main 2025 (Online) 29th January Morning ShiftMCQMedium📈 Topic in 24% papers+4−1
Ques. 1JEE Main 2025, 29 January (Morning Shift)

1.24 g of AX2 (molar mass 124 g mol-1) is dissolved in 1 kg of water to form a solution with boiling point of 100.0156°C, while 25.4 g of AY2 (molar mass 250 g mol-1) in 2 kg of water constitutes a solution with a boiling point of 100.0260°C. Kb(H2O) = 0.52 kg mol-1 Which of the following is correct?

  1. AX2 and AY2 (both) are completely unionised.
  2. AX2 and AY2 (both) are fully ionised.
  3. AX2 is completely unionised while AY2 is fully ionised.
  4. AX2 is fully ionised while AY2 is completely unionised.

Answer

(4) AX2 is fully ionised while AY2 is completely unionised.

Solution

From Tb = i Kb m we get i = TbKb m.

For AX2: m = 1.24/1241 = 0.01 mol kg-1 and Tb = 100.0156 - 100 = 0.0156 K, so

i = 0.01560.52 0.01 = 3

Hence AX2 A2+ + 2X- is complete, i.e. AX2 is fully ionised.

For AY2: m = 25.4/2502 = 0.10162 = 0.0508 mol kg-1 and Tb = 0.0260 K, so

i = 0.02600.52 0.0508 = 0.02600.0264 1

AY2 is completely unionised.

Answer: (4)

Keep practising — Solutions

Ques. 2JEE Main 2025, 29 January (Morning Shift)

If A2B is 30% ionised in an aqueous solution, then the value of van't Hoff factor (i) is 10-1.

Ques. 3JEE Main 2025, 29 January (Evening Shift)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are false
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are true
  4. Statement I is false but Statement II is true
Ques. 4JEE Main 2025, 28 January (Morning Shift)

What is the freezing point depression constant of a solvent, 50 g of which contain 1 g non-volatile solute (molar mass 256 g mol-1) and the decrease in freezing point is 0.40 K?

  1. 4.43 K kg mol-1
  2. 3.72 K kg mol-1
  3. 5.12 K kg mol-1
  4. 1.86 K kg mol-1
Ques. 5JEE Main 2025, 28 January (Evening Shift)

Assume a living cell with 0.9% (w/w) of glucose solution (aqueous). This cell is immersed in another solution having equal mole fraction of glucose and water. (Consider the data upto first decimal place only) The cell will :

  1. shrink since solution is 0.45% (w/w) as a result of association of glucose molecules (due to hydrogen bonding)
  2. shrink since solution is 0.5% (w/w)
  3. show no change in volume since solution is 0.9% (w/w)
  4. swell up since solution is 1% (w/w)
Ques. 6JEE Main 2025, 24 January (Morning Shift)

Consider the given plots of vapour pressure (VP) vs temperature (T/K). Which amongst the following options is correct graphical representation showing Tf, depression in the freezing point of a solvent in a solution?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 7JEE Main 2025, 24 January (Evening Shift)

The observed and normal molar masses of compound MX2 are 65.6 and 164 respectively. The percent degree of ionisation of MX2 is %. (Nearest integer)

Ques. 8JEE Main 2025, 23 January (Morning Shift)

CrCl3 xNH3 can exist as a complex. 0.1 molal aqueous solution of this complex shows a depression in freezing point of 0.558 C. Assuming 100% ionisation of this complex and coordination number of Cr is 6, the complex will be (Given Kf = 1.86 K kg mol-1)

  1. [Cr(NH3)5Cl]Cl2
  2. [Cr(NH3)4Cl2]Cl
  3. [Cr(NH3)6]Cl3
  4. [Cr(NH3)3Cl3]
Ques. 9JEE Main 2025, 23 January (Evening Shift)

When a non-volatile solute is added to the solvent, the vapour pressure of the solvent decreases by 10 mm of Hg. The mole fraction of the solute in the solution is 0.2. What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg ?

  1. 0.2
  2. 0.4
  3. 0.8
  4. 0.6
Ques. 10JEE Main 2025, 23 January (Evening Shift)

Consider a binary solution of two volatile liquid components 1 and 2. x1 and y1 are the mole fractions of component 1 in liquid and vapour phase, respectively. The slope and intercept of the linear plot of 1x1 vs 1y1 are given respectively as :

  1. P10P20, P10-P20P20
  2. P20P10, P20-P10P10
  3. P20P10, P10-P20P20
  4. P10P20, P20-P10P20
Ques. 11JEE Main 2025, 22 January (Morning Shift)

Arrange the following solutions in order of their increasing boiling points. (i) 10-4 M NaCl (ii) 10-4 M Urea (iii) 10-3 M NaCl (iv) 10-2 M NaCl

  1. (i) < (ii) < (iii) < (iv)
  2. (ii) < (i) < (iii) < (iv)
  3. (iv) < (iii) < (i) < (ii)
  4. (ii) < (i) (iii) < (iv)

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