JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Practical and Analytical Chemistry

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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)

Answer: 73

Solution

The

C a C l_{2}

tube absorbs water (

0.15 g

) and the potash tube absorbs

C O_{2}

(

0.1837 g

). Mass of carbon

= \frac{12}{44} \times 0.1837 = 0.0501 g

. Mass of hydrogen

= \frac{2}{18} \times 0.15 = 0.0167 g

. Mass of oxygen by difference

= 0.25 - 0.0501 - 0.0167 = 0.1832 g

. The percentage of oxygen is

\frac{0.1832}{0.25} \times 100 = 73.3%

, i.e.

73%

to the nearest integer.

JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Integer answer

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JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Practical and Analytical Chemistry

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