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Formula of a hydrocarbon from its combustion (oxygen used, CO2 and water)

This type of question, asked 3 times: 29 Jan 2023, 1 Feb 2024, 21 Jan 2026 S1. All 3 questions below, oldest first.

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  1. Question 1

    29 Jan 2023

    136
    When a hydrocarbon A undergoes combustion in the presence of air, it requires 9.5 equivalents of oxygen and produces 3 equivalents of water. What is the molecular formula of A?

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  2. Question 2

    1 Feb 2024

    150
    10 mL10\text{ }mL of gaseous hydrocarbon on combustion gives 40 mL40\text{ }mL of CO2( g)CO_{2}(\text{ }g) and 50 mL50\text{ }mL of water vapour. Total number of carbon and hydrogen atoms in the hydrocarbon is ______ .

  3. Question 3

    21 Jan 2026 S1

    31
    80 mL of a hydrocarbon on mixing with 264 mL of oxygen in a closed U-tube undergoes complete combustion. The residual gases after cooling to 273 K occupy 224 mL. When the system is treated with KOH solution, the volume decreases to 64 mL. The formula of the hydrocarbon is :

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