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Percentage of carbon, hydrogen or oxygen from the masses of CO2 and water on combustion

This type of question, asked 10 times: 26 Jun 2022, 28 Jun 2022, 28 Jul 2022, 31 Jan 2023, 8 Apr 2023, 13 Apr 2023, 3 Apr 2025, 7 Apr 2025, 24 Jan 2026 S2, 2 Apr 2026 S2. All 10 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    26 Jun 2022

    58
    On complete combustion 0.30 g0.30\text{ }g of an organic compound gave 0.20 g0.20\text{ }g of carbon dioxide and 0.10 g0.10\text{ }g of water. The percentage of carbon in the given organic compound is (Nearest Integer)

  2. Question 2

    28 Jun 2022

    148
    The complete combustion of 0.492 g0.492\text{ }g of an organic compound containing ' CC ', ' HH ' and ' OO ' gives 0.793 g0.793\text{ }g of CO2CO_{2} and 0.442 g0.442\text{ }g of H2OH_{2}O. The percentage of oxygen composition in the organic compound is . (nearest integer)

  3. Question 3

    28 Jul 2022

    60
    On complete combustion of 0.492 g0.492\text{ }g of an organic compound containing C,HC,H and O,0.7938 gO,0.7938\text{ }g of CO2CO_{2} and 0.4428 g0.4428\text{ }g of H2OH_{2}O was produced. The %\% composition of oxygen in the compound is

  4. Question 4

    31 Jan 2023

    54
    On complete combustion, 0.492 g0.492\text{ }g of an organic compound gave 0.792 g0.792\text{ }g of CO2CO_{2}. The %\% of carbon in the organic compound is (Nearest integer)

  5. Question 5

    8 Apr 2023

    57
    0.5 g0.5\text{ }g of an organic compound (X) with 60%60\% carbon will produce___ ×10−1 g\times10^{- 1}\text{ }g of CO2CO_{2} on complete combustion.

  6. Question 6

    13 Apr 2023

    55
    An organic compound gives 0.220 g0.220\text{ }g of CO2CO_{2} and 0.126 g0.126\text{ }g of H2OH_{2}O on complete combustion. If the %\% of carbon is 24 then the %\% hydrogen is___ ×10−1\times10^{- 1}. (Nearest integer)

  7. Question 7

    3 Apr 2025

    47
    0.5 g of an organic compound on combustion gave 1.46 g of CO2{CO}_{2} and 0.9 g of H2OH_{2}O. The percentage of carbon in the compound is ____ . (Nearest integer) [Given : Molar mass (in gmol−1g{mol}^{- 1} ) C:12,H:1C:12,H:1, O : 16]

  8. Question 8

    7 Apr 2025

    46
    An organic compound weighing 500 mg , produced 220 mg of CO2{CO}_{2}. on complete combustion. The percentage composition of carbon in the compound is ____ %\%. (nearest integer) (Given molar mass in gmol−1g{mol}^{- 1} of C:12,O:16C:12,O:16 )

  9. Question 9

    24 Jan 2026 S2

    46
    0.25 g of an organic compound "A" containing carbon, hydrogen and oxygen was analysed using the combustion method. There was an increase in mass of CaCl2{CaCl}_{2} tube and potash tube at the end of the experiment. The amount was found to be 0.15 g and 0.1837 g, respectively. The percentage of oxygen in compound A is ____\_\_\_\_ %. (Nearest integer) (Given: molar mass in gmol−1H:1,C:12,O:16g{mol}^{- 1}H:1,C:12,O:16 )

  10. Question 10

    2 Apr 2026 S2

    37
    Complete combustion of X g of an organic compound gave 0.25 g of CO2CO_{2} and 0.12 g of H2OH_{2}O. If the % of carbon is 25%25\% and of hydrogen is 4.89%4.89\%, then X=X = ____\_\_\_\_ ×10−3 g\times10^{- 3}\text{ }g. (Nearest integer) (Molar mass of C,HC,H and O are 12, 1 and 16 g mol−116\text{ }g{\text{ }mol}^{- 1} respectively )

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