JEE Main 2026 — Jan 24, Shift 2 — Chemistry solution

JEE Main2026Jan 24, Shift 2Chemistry

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 $CaCl_{2}$ 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 g $mol^{- 1}$ H: 1, C: 12, O: 16)

Your answer

Solution

Mass of $H_{2} O$ absorbed in $CaCl_{2}$ tube $= 0.15$ g. Mass of $CO_{2}$ absorbed in potash tube $= 0.1837$ g.

Mass of C $= \frac{12}{44} \times 0.1837 \approx 0.050$ g.

Mass of H $= \frac{2}{18} \times 0.15 \approx 0.017$ g.

Mass of O $= 0.25 - 0.050 - 0.017 = 0.183$ g.

$% O = \frac{0.183}{0.25} \times 100 \approx 73%$ .

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