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23 JEE Main questions · Chemistry

  1. ChemistryJEE Main 21 Jan 2026, Shift 1·Q9·MCQ·Moderate
    Open

    Elevation of boiling point

    Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and PQX2\ce{PQ2}. When 1 g of PQ is dissolved in 50 g of solvent ‘A'. ΔTb\Delta T_\mathrm{b} was 1.176 K while when 1 g of PQX2\ce{PQ2} is dissolved in 50 g of solvent ‘A', ΔTb\Delta T_\mathrm{b} was 0.689 K. (KbK_\mathrm{b} of ‘A' =5= 5 K kg mol−1^{-1}). The molar masses of elements P and Q (in g mol−1^{-1}) respectively, are :
    1. (1)70, 110
    2. (2)65, 145
    3. (3)60, 25
    4. (4)25, 60
  2. ChemistryJEE Main 21 Jan 2026, Shift 2·Q22·Numerical·Easy–moderate
    Open

    Osmotic pressure isotonic solutions

    The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is g L−1^{-1}. (Nearest integer)

    Given : R=0.08R = 0.08 L atm K−1^{-1} mol−1^{-1}

    Assume complete dissociation of NaCl

    (Given : Molar mass of Na and Cl are 23 and 35.5 g mol−1^{-1} respectively.)

    We corrected a printing error in the original paper

    Source printed “The osmotic pressure of a living cell in 12 atm”.

  3. ChemistryJEE Main 21 Jan 2026, Shift 2·Q23·Numerical·Moderate
    Open

    Relative lowering of vapour pressure

    A substance ‘X' (1.5 g) dissolved in 150 g of a solvent ‘Y' (molar mass =300= 300 g mol−1^{-1}) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent ‘Y' is ×10−2\times10^{-2}. (Nearest integer)

    [Given : KbK_\mathrm{b} of the solvent =5.0= 5.0 K kg mol−1^{-1}]

    Assume the solution to be dilute and no association or dissociation of X takes place in solution.

  4. ChemistryJEE Main 22 Jan 2026, Shift 1·Q7·MCQ·Easy–moderate
    Open

    Henry law logarithmic plot

    Consider a solution of COX2(g)\ce{CO2(g)} dissolved in water in a closed container.

    Which one of the following plots correctly represents variation of log (partial pressure of COX2\ce{CO2} in vapour phase above water) [y-axis] with log (mole fraction of COX2\ce{CO2} in water) [x-axis] at 25 ∘^\circC ?

    1. (1)
    2. (2)
    3. (3)
    4. (4)
  5. ChemistryJEE Main 22 Jan 2026, Shift 1·Q20·MCQ·Easy
    Open

    Henry law constant

    Given below are two statements:

    Statement I : The Henry's law constant KHK_\mathrm{H} is constant with respect to variations in solution's concentration over the range for which the solution is ideally dilute.

    Statement II : KHK_\mathrm{H} does not differ for the same solute in different solvents.

    In the light of the above statements, choose the correct answer from the options.

    1. (1)Statement I is false but Statement II is true.
    2. (2)Statement I is true but Statement II is false.
    3. (3)Both Statement I and Statement II are true.
    4. (4)Both Statement I and Statement II are false.
    We corrected a printing error in the original paper

    Source printed “over the range for which the solutions is ideally dilute”.

  6. ChemistryJEE Main 23 Jan 2026, Shift 1·Q2·MCQ·Easy–moderate
    Open

    Non-ideal solutions positive deviation

    Which one of the following graphs accurately represents the plot of partial pressure of CSX2\ce{CS2} vs its mole fraction in a mixture of acetone and CSX2\ce{CS2} at constant temperature ?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  7. ChemistryJEE Main 23 Jan 2026, Shift 2·Q22·Numerical·Easy–moderate
    Open

    Raoult law vapour pressure

    Two liquids A and B form an ideal solution. At 320 K, the vapour pressure of the solution, containing 3 mol of A and 1 mol of B is 500 mm Hg. At the same temperature, if 1 mol of A is further added to this solution, vapour pressure of the solution increases by 20 mm Hg. Vapour pressure (in mm Hg) of B in the pure state is . (Nearest integer)
  8. ChemistryJEE Main 24 Jan 2026, Shift 1·Q5·MCQ·Easy–moderate
    Open

    Osmotic pressure of mixed solutes

    A solution is prepared by dissolving 0.3 g of a non-volatile non-electrolyte solute ‘A' of molar mass 60 g mol−1^{-1} and 0.9 g of a non-volatile non-electrolyte solute ‘B' of molar mass 180 g mol−1^{-1} in 100 mL HX2O\ce{H2O} at 27∘^\circC. Osmotic pressure of the solution will be

    [Given : R=0.082R = 0.082 L atm K−1^{-1} mol−1^{-1}]

    1. (1)1.23 atm
    2. (2)2.46 atm
    3. (3)0.82 atm
    4. (4)1.47 atm
  9. ChemistryJEE Main 24 Jan 2026, Shift 1·Q12·MCQ·Moderate
    Open

    Colligative properties van't hoff factor

    ‘W' g of a non-volatile electrolyte solid solute of molar mass ‘M' g mol−1^{-1} when dissolved in 100 mL water, decreases vapour pressure of water from 640 mm Hg to 600 mm Hg. If aqueous solution of the electrolyte boils at 375 K and KbK_\mathrm{b} for water is 0.52 K kg mol−1^{-1}, then the mole fraction of the electrolyte solute (x2x_2) in the solution can be expressed as

    (Given : density of water = 1 g/mL and boiling point of water = 373 K)

    1. (1)1.38×WM\dfrac{1.3}{8}\times\dfrac{\mathrm{W}}{\mathrm{M}}
    2. (2)162.6×WM\dfrac{16}{2.6}\times\dfrac{\mathrm{W}}{\mathrm{M}}
    3. (3)2.616×MW\dfrac{2.6}{16}\times\dfrac{\mathrm{M}}{\mathrm{W}}
    4. (4)1.38×MW\dfrac{1.3}{8}\times\dfrac{\mathrm{M}}{\mathrm{W}}
  10. ChemistryJEE Main 24 Jan 2026, Shift 2·Q4·MCQ·Easy–moderate
    Open

    Raoult law vapour composition

    Two liquids A and B form an ideal solution at temperature T K. At T K, the vapour pressures of pure A and B are 55 and 15 kN m−2^{-2} respectively. What is the mole fraction of A in solution of A and B in equilibrium with a vapour in which the mole fraction of A is 0.8 ?
    1. (1)0.5217
    2. (2)0.480
    3. (3)0.663
    4. (4)0.340
  11. ChemistryJEE Main 24 Jan 2026, Shift 2·Q18·MCQ·Easy–moderate
    Open

    Henry law gas solubility

    At 298 K, the mole percentage of NX2(g)\ce{N2(g)} in air is 80%. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of NX2(g)\ce{N2(g)} in water at 298 K ? (KHK_\mathrm{H} for NX2\ce{N2} is 6.5×1076.5\times10^{7} mm Hg)
    1. (1)1.23×10−71.23\times10^{-7}
    2. (2)1.17×10−41.17\times10^{-4}
    3. (3)9.35×1059.35\times10^{5}
    4. (4)9.35×10−59.35\times10^{-5}
  12. ChemistryJEE Main 28 Jan 2026, Shift 1·Q3·MCQ·Moderate
    Open

    Raoult's law vapour pressure

    At T(K), 2 moles of liquid A and 3 moles of liquid B are mixed. The vapour pressure of ideal solution formed is 320 mm Hg. At this stage, one mole of A and one mole of B are added to the solution. The vapour pressure is now measured as 328.6 mm Hg. The vapour pressures (in mm Hg) of A and B are respectively:
    1. (1)300, 200
    2. (2)600, 400
    3. (3)400, 300
    4. (4)500, 200
    We corrected a printing error in the original paper

    Source printed “The vapour pressure (in mm Hg) of A and B are”.

  13. ChemistryJEE Main 28 Jan 2026, Shift 2·Q14·MCQ·Moderate
    Open

    Elevation of boiling point

    Consider the following aqueous solutions.
    • (I)2.2 g Glucose in 125 mL of solution.
    • (II)1.9 g Calcium chloride in 250 mL of solution.
    • (III)9.0 g Urea in 500 mL of solution.
    • (IV)20.5 g Aluminium sulphate in 750 mL of solution.

    The correct increasing order of boiling point of these solutions will be:

    [Given: Molar mass in g mol−1^{-1}: H=1=1, C=12=12, N=14=14, O=16=16, Cl=35.5=35.5, Ca=40=40, Al=27=27 and S=32=32]

    1. (1)I << II << III << IV
    2. (2)III << I << II << IV
    3. (3)II << III << I << IV
    4. (4)II << III << IV << I
  14. ChemistryJEE Main 2 Apr 2026, Shift 1·Q5·MCQ·Moderate
    Open

    Freezing point depression and dissociation

    19.5 g of fluoro acetic acid (molar mass = 78 g mol−1^{-1}) is dissolved in 500g of water at 298 K. The depression in the freezing point of water was 1∘^\circC. What is KaK_\mathrm{a} of fluoro acetic acid ?

    (For water, Kf=1.86K_\mathrm{f} = 1.86 K kg mol−1^{-1}). Assume molarity and molality to have same values.

    1. (1)10−610^{-6}
    2. (2)4×10−44\times10^{-4}
    3. (3)3×10−53\times10^{-5}
    4. (4)3×10−33\times10^{-3}
  15. ChemistryJEE Main 2 Apr 2026, Shift 2·Q5·MCQ·Easy–moderate
    Open

    Osmotic pressure of mixed solutions

    Solution A is prepared by dissolving 1 g of a protein (molar mass = 50000 g mol−1^{-1}) in 0.5 L of water at 300 K. Its osmotic pressure is x bar. Solution B is made by dissolving 2 g of same protein in 1 L of water at 300 K. Osmotic pressure of solution B is y bar. Entire solution of A is mixed with entire solution of B at same temperature. The osmotic pressure of resultant solution is z bar. x, y and z respectively are :

    (R=0.083R = 0.083 L bar mol−1^{-1} K−1^{-1})

    1. (1)9.96×10−49.96\times10^{-4}; 9.96×10−49.96\times10^{-4}; 9.96×10−49.96\times10^{-4}
    2. (2)9.96×10−49.96\times10^{-4}; 9.96×10−49.96\times10^{-4}; 19.92×10−419.92\times10^{-4}
    3. (3)4.98×10−44.98\times10^{-4}; 4.98×10−44.98\times10^{-4}; 9.96×10−49.96\times10^{-4}
    4. (4)4.98×10−44.98\times10^{-4}; 4.98×10−44.98\times10^{-4}; 4.98×10−44.98\times10^{-4}
  16. ChemistryJEE Main 4 Apr 2026, Shift 1·Q25·Numerical·Moderate
    Open

    Colligative properties vapour pressure

    A non-volatile, non-electrolyte solid solute when dissolved in 40 g of a solvent, the vapour pressure of the solvent decreased from 760 mm Hg to 750 mm Hg. If the same solution boils at 320 K, then the number of moles of the solvent present in the solution is . (Nearest integer)

    [Given : boiling point of the pure solvent =319.5= 319.5 K, KbK_\mathrm{b} of the solvent =0.3= 0.3 K kg mol−1^{-1}]

  17. ChemistryJEE Main 4 Apr 2026, Shift 2·Q4·MCQ·Moderate
    Open

    Osmosis and osmotic pressure

    At 27∘^\circC, 0.1 M, 1 L KX4[Fe(CN)X6]\ce{K4[Fe(CN)6]} aqueous solution and 0.1 M, 1 L FeClX3\ce{FeCl3} aqueous solution are placed in a container separated by a semi permeable membrane AB. Assume complete dissociation of both the solutes. Which of the following statement is correct ?
    1. (1)Blue color is formed on both sides.
    2. (2)Ionic solutes in aqueous solution can pass through semi-permeable membrane.
    3. (3)Solution on side ‘y' is hypotonic.
    4. (4)To cause the reverse flow of solvent during osmosis, external pressure (any value) should be applied to side ‘x'.
  18. ChemistryJEE Main 5 Apr 2026, Shift 1·Q4·MCQ·Easy–moderate
    Open

    Mole fraction from mass percent

    What is the mole fraction of water in 10% by weight (w/w) of aqueous urea solution ?

    [Given : Molar mass of H, O, C and N are 1, 16, 12 and 14 g mol−1^{-1} respectively]

    1. (1)0.825
    2. (2)0.032
    3. (3)0.867
    4. (4)0.967
  19. ChemistryJEE Main 5 Apr 2026, Shift 2·Q23·Numerical·Moderate
    Open

    Osmotic pressure molar mass

    20 g hemoglobin in a 1 L aqueous solution (A) at 300 K is separated from pure water by semi permeable membrane. At equilibrium the height of solution in a tube dipped in a solution (A) is found to be 80.0 mm higher than the tube dipped in water.

    The molar mass of hemoglobin is kg mol−1^{-1}. (Nearest integer)

    (Given : g=10g = 10 m s−2^{-2}, R=8.3R = 8.3 kPa dm3^3 K−1^{-1} mol−1^{-1}, density of solution =1000= 1000 kg m−3^{-3})

  20. ChemistryJEE Main 6 Apr 2026, Shift 1·Q6·MCQ·Easy–moderate
    Open

    Relative lowering of vapour pressure

    When 0.25 moles of a non-volatile, non-ionizable solute was dissolved in 1 mole of a solvent the vapor pressure of solution was x% of vapor pressure of pure solvent. What is x% ?
    1. (1)50%
    2. (2)60%
    3. (3)70%
    4. (4)80%
  21. ChemistryJEE Main 6 Apr 2026, Shift 2·Q5·MCQ·Moderate
    Open

    Osmosis and osmotic pressure

    Given below are two statements :
    Chamber 1Chamber 2
    18 g glucose in 100 mL aqueous solutionSemi-permeable membrane30 g glucose in 250 mL aqueous solution

    Statement I : HX2O\ce{H2O} molecules move from the chamber 1 to chamber 2.

    Statement II : The osmotic pressure of a solution prepared by dissolving 50 mg of potassium sulphate (molar mass = 174 g/mol) in 2 L of water (at 27∘^\circC) is 0.0107 bar. (Given : R=0.083R = 0.083 dm3^3 bar K−1^{-1} mol−1^{-1} and assume complete dissociation of electrolyte)

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

    1. (1)Both Statement I and Statement II are true
    2. (2)Both Statement I and Statement II are false
    3. (3)Statement I is true but Statement II is false
    4. (4)Statement I is false but Statement II is true
  22. ChemistryJEE Main 8 Apr 2026, Shift 2·Q2·MCQ·Easy–moderate
    Open

    Mole fraction and raoult deviations

    Given below are two statements :

    Given : Molar mass of C, H, O, Cl are 12, 1, 16 and 35.5 g mol−1^{-1}, respectively.

    Statement I : In 30%(w/w) solution of methanol in CClX4\ce{CCl4} (at T K), the mole fraction of CClX4\ce{CCl4} is equal to 0.33.

    Statement II : Mixture of methanol and CClX4\ce{CCl4} shows positive deviation from Raoult's law.

    In the light of the above statements, choose the correct answer from the option given below :

    1. (1)Both Statement I and Statement II are true
    2. (2)Both Statement I and Statement II are false
    3. (3)Statement I is true but Statement II are false
    4. (4)Statement I is false but Statement II are true
    We corrected a printing error in the original paper

    Source printed “shows positive deviation deviation from Raoult's law” and “are ture” in options (1) and (4).

  23. ChemistryJEE Main 8 Apr 2026, Shift 2·Q4·MCQ·Easy–moderate
    Open

    Colligative properties

    Which of the following are not correct ?
    • (A)For water, magnitude of KbK_\mathrm{b} is more than the magnitude of KfK_\mathrm{f}.
    • (B)The elevation in boiling point of water when a non-volatile solute is added to it is larger in magnitude than its depression in freezing point.
    • (C)Osmotic pressure measurement is preferred over any other colligative property to determine molar mass of proteins and polymers.
    • (D)The dimerised form of benzoic acid in benzene is
    Choose the correct answer from the options given below :
    1. (1)A and B only
    2. (2)A and D only
    3. (3)A, B and D only
    4. (4)A, C and D only
    We corrected a printing error in the original paper

    Source printed “non-volative solute”.