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JEE Mains Chemistry. Try each one first, then open its answer.

Top 10 JEE Mains PYQs to practise first

The questions and kinds of question asked most often come first. Each one says how often and in which papers.

  1. Question 1

    This type asked 7 times: 27 Jul 2022, 6 Apr 2023, 11 Apr 2023, 12 Apr 2023, 15 Apr 2023, 23 Jan 2025, 6 Apr 2026 S1. This one: 6 Apr 2026 S1 See all 7 of this type

    31
    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%x\% of vapor pressure of pure solvent. What is the value of x%x\%?

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  2. Question 2

    This type asked 6 times: 26 Jun 2022, 29 Jun 2022, 25 Jul 2022, 11 Apr 2023, 8 Apr 2024, 2 Apr 2026 S1. This one: 2 Apr 2026 S1 See all 6 of this type

    30
    19.5 g of fluoro acetic acid (molar mass =78 g mol−1= 78\text{ }g{\text{ }mol}^{- 1} ) is dissolved in 500 g of water at 298 K . The depression in the freezing point of water was 1∘C1^{\circ}C. What is KaK_{a} of fluoro acetic acid ? (For water, Kf=1.86 K kg mol−1K_{f}= 1.86\text{ }K\text{ }kg{\text{ }mol}^{- 1} ). Assume molarity and molality to have same values.

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  3. Question 3

    This type asked 5 times: 28 Jun 2022, 31 Jan 2023, 10 Apr 2023, 13 Apr 2023, 5 Apr 2026 S2. This one: 5 Apr 2026 S2 See all 5 of this type

    48
    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 ____\_\_\_\_ kgmol−1kg{mol}^{- 1}.(Nearest integer) (Given : g=10 ms−2,R=8.3kPadm3 K−1 mol−1g = 10{\text{ }ms}^{- 2},R = 8.3kPa{dm}^{3}{\text{ }K}^{- 1}{\text{ }mol}^{- 1}, density of solution =1000 kg m−3= 1000\text{ }kg{\text{ }m}^{- 3} )

  4. Question 4

    This type asked 5 times: 2021 Paper 13, 2021 Paper 22, 30 Jan 2024, 22 Jan 2025, 28 Jan 2026 S2. This one: 28 Jan 2026 S2 See all 5 of this type

    39
    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 Aluminum sulphate in 750 mL of solution. The correct increasing order of boiling point of these solutions will be: [Given: Molar mass in gmol−1:H=1,C=12, N=14gmol^{- 1}:H = 1,C = 12,\text{ }N = 14, O=16,Cl=35.5,Ca=40,Al=27O = 16,Cl = 35.5,Ca = 40,Al = 27 and S=32S = 32 ]

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  5. Question 5

    This type asked 5 times: 28 Jul 2022, 24 Jan 2023, 2 Apr 2025, 23 Jan 2026 S2, 28 Jan 2026 S1. This one: 28 Jan 2026 S1 See all 5 of this type

    28
    At T(K),2T(K),2 moles of liquid A and 3 moles of liquid BB are mixed. The vapour pressure of ideal solution formed is 320 mm Hg . At this stage, one mole of A and one mole of BB are added to the solution. The vapor pressure is now measured as 328.6 mm Hg . The vapour pressure (in mm Hg ) of A and B are respectively:

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  6. Question 6

    This type asked 5 times: 30 Jan 2023, 1 Feb 2023, 13 Apr 2023, 5 Apr 2024, 6 Apr 2024. This one: 6 Apr 2024 See all 5 of this type

    51
    Consider the dissociation of the weak acid HX as given below
    HX(aq)⇌H+(aq)+X−(aq),Ka=1.2×10−5HX(aq) \rightleftharpoons H^{+}(aq) +X^{-}(aq),Ka = 1.2 \times10^{- 5}
    [Ka:\left\lbrack K_{a}: \right. dissociation constant ]\rbrack The osmotic pressure of 0.03M0.03M aqueous solution of HXHX at 300 K300\text{ }K is ____ ×10−2\times10^{- 2} bar (nearest integer). [Given: R=0.083 LbarMol−1 K−1R = 0.083\text{ }LbarMol^{- 1}{\text{ }K}^{- 1} ]

  7. Question 7

    This type asked 4 times: 27 Jan 2024, 31 Jan 2024, 23 Jan 2026 S1, 8 Apr 2026 S2. This one: 8 Apr 2026 S2 See all 4 of this type

    27
    Given below are two statements : Given : Molar mass of C,H,O,ClC,H,O,Cl are 12,1,1612,1,16 and 35.5 g mol−135.5\text{ }g{\text{ }mol}^{- 1}, respectively. Statement I : In 30%(w/w)30\%(w/w) solution of methanol in CCl4{CCl}_{4} (at T K ), the mole fraction of CCl4{CCl}_{4} is equal to 0.33 . Statement II : Mixture of methanol and CCl4{CCl}_{4} shows positive deviation from Raoult's law. In the light of the above statements, choose the correct answer from the option given below :

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  8. Question 8

    This type asked 4 times: 4 Apr 2024, 21 Jan 2026 S2, 24 Jan 2026 S1, 4 Apr 2026 S1. This one: 4 Apr 2026 S1 See all 4 of this type

    50
    A non-volatile, non-electrolyte solid solute when dissolved in 40 g of a solvent, the vapor 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 K, Kb= 319.5\text{ }K,{\text{ }K}_{b} of the solvent =0.3 K kg mol−1= 0.3\text{ }K\text{ }kg{\text{ }mol}^{- 1} ]

  9. Question 9

    This type asked 4 times: 2021 Paper 11, 28 Jun 2022, 9 Apr 2024, 24 Jan 2026 S2. This one: 24 Jan 2026 S2 See all 4 of this type

    29
    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 15kNm−215kNm^{- 2} respectively. What is the mole fraction of A in solution of A and BB in equilibrium with a vapour in which the mole fraction of A is 0.8 ?

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  10. Question 10

    This type asked 4 times: 10 Apr 2023, 24 Jan 2025, 29 Jan 2025, 7 Apr 2025. This one: 7 Apr 2025 See all 4 of this type

    49
    The percentage dissociation of a salt (MX3)\left( {MX}_{3} \right) solution at given temperature (van't Hoff factor i = 2) is ____ % (Nearest integer)