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JEE Main 2025 (Online) 4th April Evening ShiftNumericalMedium📈 Topic in 14% papers+4
Ques. 1JEE Main 2025, 4 April (Evening Shift)

Sea water, which can be considered as a 6 molar (6 M) solution of NaCl, has a density of 2 g mL-1. The concentration of dissolved oxygen (O2) in sea water is 5.8 ppm. Then the concentration of dissolved oxygen (O2) in sea water, in terms of molality, is x 10-4 m. x = . (Nearest integer) Given: Molar mass of NaCl is 58.5 g mol-1 Molar mass of O2 is 32 g mol-1

Answer

2

Solution

Take 1 L (1000 mL) of sea water. The mass of solution is 1000 2 = 2000 g and the mass of NaCl is 6 58.5 = 351 g, so the mass of water (solvent) is

2000 - 351 = 1649 g = 1.649 kg

5.8 ppm means 5.8 g of O2 in 106 g of solution, so the mass of O2 in 2000 g solution is

5.8 2000106 = 0.0116 g

and the moles of O2 are 0.011632 = 3.625 10-4 mol.

Molality = 3.625 10-41.649

= 2.2 10-4 m

x 2

Answer: 2

Keep practising — Solutions

Ques. 2JEE Main 2025, 3 April (Morning Shift)

2 moles each of ethylene glycol and glucose are dissolved in 500 g of water. The boiling point of the resulting solution is: (Given : Ebullioscopic constant of water = 0.52 K kg mol-1)

  1. 377.3 K
  2. 379.2 K
  3. 375.3 K
  4. 277.3 K
Ques. 3JEE Main 2025, 2 April (Morning Shift)

A solution is made by mixing one mole of volatile liquid A with 3 moles of volatile liquid B. The vapour pressure of pure A is 200 mm Hg and that of the solution is 500 mm Hg. The vapour pressure of pure B and the least volatile component of the solution, respectively, are:

  1. 1400 mm Hg, A
  2. 1400 mm Hg, B
  3. 600 mm Hg, A
  4. 600 mm Hg, B
Ques. 4JEE Main 2025, 2 April (Morning Shift)

Which of the following graph correctly represents the plots of KH at 1 bar for gases in water versus temperature?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 5JEE Main 2025, 2 April (Evening Shift)

When 1 g each of compounds AB and AB2 are dissolved in 15 g of water separately, they increased the boiling point of water by 2.7 K and 1.5 K respectively. The atomic mass of A (in amu) is 10-1 (Nearest integer) (Given : Molal boiling point elevation constant is 0.5 K kg mol-1)

Ques. 6JEE 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.
Ques. 7JEE 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. 8JEE 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. 9JEE 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. 10JEE 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. 11JEE 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]

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