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JEE Main 2024 (Online) 6th April Evening ShiftNumericalMedium📈 Topic in 14% papers+4
Ques. 1JEE Main 2024, 6 April (Evening Shift)

When 'x' 10-2 mL methanol (molar mass = 32 g, density = 0.792 g/cm3) is added to 100 mL water (density = 1 g/cm3), the following diagram is obtained. [figure] x = (nearest integer). [Given : Molal freezing point depression constant of water at 273.15 K is 1.86 K kg mol-1]

Answer

543

Solution

∵ the solution freezes where its vapour pressure curve meets that of the frozen system (ice)

Tf = 273.15 - 270.65 = 2.5 K; mass of water = 100 g = 0.1 kg

Tf = Kf m 2.5 = 1.86 n0.1

n = 0.1344 mol

Mass of methanol = 0.1344 32 = 4.30 g

Volume = 4.300.792 = 5.43 mL = 543 10-2 mL

Answer: 543

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Ques. 2JEE Main 2024, 5 April (Morning Shift)

An artificial cell is made by encapsulating 0.2 M glucose solution within a semipermeable membrane. The osmotic pressure developed when the artificial cell is placed within a 0.05 M solution of NaCl at 300 K is 10-1 bar. (nearest integer). [Given : R = 0.083 L bar mol-1 K-1] Assume complete dissociation of NaCl

Ques. 3JEE Main 2024, 5 April (Evening Shift)

Considering acetic acid dissociates in water, its dissociation constant is 6.25 10-5. If 5 mL of acetic acid is dissolved in 1 litre water, the solution will freeze at -x 10-2 C, provided pure water freezes at 0 C. x = . (Nearest integer) Given : (Kf)water = 1.86 K kg mol-1 density of acetic acid is 1.2 g mL-1. molar mass of water = 18 g mol-1. molar mass of acetic acid = 60 g mol-1. density of water = 1 g cm-3 Acetic acid dissociates as CH3COOH CH3COO + H

Ques. 4JEE Main 2024, 4 April (Morning Shift)

2.5 g of a non-volatile, non-electrolyte is dissolved in 100 g of water at 25 . The solution showed a boiling point elevation by 2 . Assuming the solute concentration is negligible with respect to the solvent concentration, the vapor pressure of the resulting aqueous solution is mm of Hg (nearest integer) [Given : Molal boiling point elevation constant of water (Kb) = 0.52 K kg mol-1, 1 atm pressure = 760 mm of Hg, molar mass of water = 18 g mol-1]

Ques. 5JEE Main 2024, 4 April (Evening Shift)

2.7 kg of each of water and acetic acid are mixed. The freezing point of the solution will be -x C. Consider the acetic acid does not dimerise in water, nor dissociates in water. x = (nearest integer) [Given: Molar mass of water = 18 g mol-1, acetic acid = 60 g mol-1 Kf H2O : 1.86 K kg mol-1 Kf acetic acid: 3.90 K kg mol-1 freezing point: H2O = 273 K, acetic acid = 290 K]

Ques. 6JEE Main 2024, 1 February (Morning Shift)

We have three aqueous solutions of NaCl labelled as 'A', 'B' and 'C' with concentration 0.1 M, 0.01 M and 0.001 M, respectively. The value of van 't Hoff factor (i) for these solutions will be in the order :

  1. iA < iC < iB
  2. iA < iB < iC
  3. iA > iB > iC
  4. iA = iB = iC
Ques. 7JEE Main 2024, 1 February (Evening Shift)

Mass of ethylene glycol (antifreeze) to be added to 18.6 kg of water to protect the freezing point at -24 is kg (Molar mass in g mol-1 for ethylene glycol 62, Kf of water = 1.86 K kg mol-1)

Ques. 8JEE Main 2024, 31 January (Morning Shift)

Identify the mixture that shows positive deviations from Raoult's Law

  1. (CH3)2CO + CS2
  2. (CH3)2CO + C6H5NH2
  3. CHCl3 + C6H6
  4. CHCl3 + (CH3)2CO
Ques. 9JEE Main 2024, 30 January (Morning Shift)

What happens to freezing point of benzene when small quantity of naphthalene is added to benzene?

  1. Increases
  2. Decreases
  3. Remains unchanged
  4. First decreases and then increases
Ques. 10JEE Main 2024, 30 January (Evening Shift)

The solution from the following with highest depression in freezing point/lowest freezing point is

  1. 180 g of acetic acid dissolved in benzene
  2. 180 g of acetic acid dissolved in water
  3. 180 g of benzoic acid dissolved in benzene
  4. 180 g of glucose dissolved in water
Ques. 11JEE Main 2024, 30 January (Evening Shift)

If a substance 'A' dissolves in solution of a mixture of 'B' and 'C' with their respective number of moles as nA, nB and nC. Mole fraction of C in the solution is

  1. nCnA nB nC
  2. nBnA+nB
  3. nCnA+nB+nC
  4. nCnA-nB-nC

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