JEE MAIN - Chemistry (2025 - 8th April Evening Shift - No. 9)
On combustion 0.210 g of an organic compound containing C, H and O gave 0.127 g H2O and 0.307 g CO2. The percentages of hydrogen and oxygen in the given organic compound respectively are:
7.55, 43.85
6.72, 53.41
6.72, 39.87
53.41, 39.6
Explanation
In the combustion of organic compound, all "C" in $\mathrm{CO}_2$ and all " H " in $\mathrm{H}_2 \mathrm{O}$ comes from organic compound
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Weight of " C " in $\mathrm{CO}_2=\frac{12}{44} \times 0.307$
$$=0.0837 \mathrm{~gm}$$
Weight of " H " in $\mathrm{H}_2 \mathrm{O}=\frac{2}{18} \times 0.127=0.0141 \mathrm{~g}$
$$\begin{aligned} &\begin{gathered} \% ' H^{\prime} \text { in compound }=\frac{0.0141}{0.21} \times 100=6.719 \% \\ =6.72 \% \end{gathered}\\ &\text { Weight of "O" in compound }\\ &\begin{aligned} & =0.210-(0.0837+0.0141) \\ & =0.1122 \end{aligned}\\ &\begin{aligned} & \% \text { of "O" in compound }=\frac{0.1122}{0.21} \times 100 \\ & =53.41 \% \end{aligned} \end{aligned}$$
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