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Some Basic Concepts of Chemistry

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 14 times: 2021 Paper 21, 26 Jun 2022, 29 Jun 2022, 28 Jul 2022, 29 Jul 2022, 31 Jan 2023, 6 Apr 2023, 1 Feb 2024, 23 Jan 2025, 24 Jan 2025, 2 Apr 2025, 7 Apr 2025, 22 Jan 2026 S2, 28 Jan 2026 S2. This one: 28 Jan 2026 S2 See all 14 of this type

    43
    For the given reaction;
    CaCO3+2HCl→CaCl2+H2O+CO2CaCO_{3}+ 2HCl \rightarrow CaCl_{2}+H_{2}O +CO_{2}
    If 90 gCaCO390\text{ }gCaCO_{3} is added to 300 mL of HCl which contains 38.55%HCl38.55\% HCl by mass and has density 1.13 g mL−11.13\text{ }g{\text{ }mL}^{- 1}, then which of the following option is correct? Given molar mass of H,Cl,CaH,Cl,Ca and O are 1, 35.5, 40 and 16 g mol−116\text{ }g{\text{ }mol}^{- 1} respectively.

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  2. Question 2

    This type asked 11 times: 25 Jun 2022, 27 Jul 2022, 28 Jul 2022, 25 Jan 2023, 29 Jan 2023, 6 Apr 2023, 13 Apr 2023, 29 Jan 2024, 22 Jan 2025, 3 Apr 2025, 23 Jan 2026 S1. This one: 23 Jan 2026 S1 See all 11 of this type

    48
    x mg of pure HCl was used to make an aqueous solution. 25.0 mL of 0.1MBa(OH)20.1MBa(OH)_{2} solution is used when the HCl solution was titrated against it. The numerical value of xx is ____\_\_\_\_ ×10−1\times 10^{- 1}. (Nearest integer) Given : Molar mass of HCl and Ba(OH)2Ba(OH)_{2} are 36.5 and 171.0 g mol−1171.0\text{ }g{\text{ }mol}^{- 1} respectively.

  3. Question 3

    This type asked 10 times: 2021 Paper 24, 25 Jun 2022, 26 Jul 2022, 10 Apr 2023, 30 Jan 2024, 3 Apr 2025, 4 Apr 2026 S1, 4 Apr 2026 S2, 6 Apr 2026 S2, 8 Apr 2026 S2. This one: 8 Apr 2026 S2 See all 10 of this type

    26
    Match List-I with List-II.
    List-I Mass of substanceList-II Number of atoms
    (A)1.8mg1.8mg water(I)
    2×10−4×NA2 \times 10^{- 4} \times N_{A}
    (B)9.8mg9.8mg sulphuric acid(II)
    1.5×10−4×NA1.5 \times 10^{- 4} \times N_{A}
    (C)1.8 mg carbon(III)
    3×10−4×NA3 \times 10^{- 4} \times N_{A}
    (D)5.85 mg salt (NaCl)(NaCl)(IV)
    7×10−4×NA7 \times 10^{- 4} \times N_{A}
    Choose the correct answer from the options given below:

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  4. Question 4

    This type asked 9 times: 2021 Paper 13, 2021 Paper 19, 2021 Paper 22, 2021 Paper 23, 2021 Paper 24, 2021 Paper 26, 27 Jan 2024, 30 Jan 2024, 4 Apr 2024. This one: 4 Apr 2024 See all 9 of this type

    48
    The Molarity (M) of an aqueous solution containing 5.85 g5.85\text{ }g of NaClNaCl in 500 mL500\text{ }mL water is: (Given: Molar Mass Na:23Na:23 and Cl:35.5 g mol−1Cl:35.5\text{ }g\text{ }mol^{- 1} )

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  5. Question 5

    This type asked 8 times: 25 Jun 2022, 29 Jul 2022, 13 Apr 2023, 24 Jan 2025, 4 Apr 2025, 21 Jan 2026 S2, 2 Apr 2026 S1, 5 Apr 2026 S1. This one: 5 Apr 2026 S1 See all 8 of this type

    26
    How many grams of residue is obtained by heating 2.76 g of silver carbonate? (Given : Molar mass of C,OC,O and Ag are 12, 16 and 108 g mol−1108\text{ }g{\text{ }mol}^{- 1} respectively)

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  6. Question 6

    This type asked 8 times: 2021 Paper 14, 2021 Paper 17, 2021 Paper 20, 28 Jun 2022, 27 Jul 2022, 4 Apr 2024, 23 Jan 2026 S2, 4 Apr 2026 S1. This one: 4 Apr 2026 S1 See all 8 of this type

    31
    In order to oxidise a mixture of 1 mole each of FeC2O4,Fe2(C2O4)3,FeSO4FeC_{2}O_{4},Fe_{2}\left( C_{2}O_{4} \right)_{3},FeSO_{4} and Fe2(SO4)3Fe_{2}\left( SO_{4} \right)_{3} in acidic medium, the number of moles of KMnO4KMnO_{4} required is :

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  7. Question 7

    This type asked 7 times: 2021 Paper 16, 27 Jul 2022, 1 Feb 2023, 29 Jan 2024, 6 Apr 2024, 9 Apr 2024, 22 Jan 2025. This one: 22 Jan 2025 See all 7 of this type

    111
    Density of 3 M NaCl solution is 1.25 g/mL1.25\text{ }g/mL. The molality of the solution is :

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  8. Question 8

    This type asked 7 times: 2021 Paper 14, 14 Jun 2022, 26 Jun 2022, 27 Jan 2024, 31 Jan 2024, 5 Apr 2024, 8 Apr 2024. This one: 8 Apr 2024 See all 7 of this type

    33
    Combustion of glucose (C6H12O6)\left( C_{6}H_{12}O_{6} \right) produces CO2CO_{2} and water. The amount of oxygen (in gg ) required for the complete combustion of 900 g900\text{ }g of glucose is: [Molar mass of glucose in mol−1=180mol^{- 1}= 180 ]

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  9. Question 9

    This type asked 6 times: 28 Jun 2022, 25 Jan 2023, 5 Apr 2024, 24 Jan 2025, 28 Jan 2025, 6 Apr 2026 S1. This one: 6 Apr 2026 S1 See all 6 of this type

    26
    An oxide of iron contains 69.9%69.9\% iron, its empirical formula, is : (Given : Molar mass of Fe and O are 56 and 16 g mol−116\text{ }g{\text{ }mol}^{- 1} respectively.)

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  10. Question 10

    This type asked 6 times: 31 Jan 2023, 11 Apr 2023, 3 Apr 2025, 21 Jan 2026 S1, 22 Jan 2026 S1, 5 Apr 2026 S2. This one: 5 Apr 2026 S2 See all 6 of this type

    26
    What volume of hydrogen gas at STP would be liberated by action of 50 mL of H2SO4H_{2}SO_{4} of 50%50\% purity (density =1.3 g mL−1= 1.3\text{ }g{\text{ }mL}^{- 1} ) on 20 g of zinc? Given : Molar mass of H, O, S, Zn are 1, 16, 32, 65 gmol−1gmol^{- 1} respectively.

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