Chemistry · Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry

JEE Main 2025 — 23 January, Evening Shift — Question 43

$0.01$ mole of an organic compound $(X)$ containing $10\%$ hydrogen, on complete combustion, produced $0.9\,\mathrm{g}$ of $\mathrm{H_2O}$ .

Find the molar mass of $(X)$ in $\mathrm{g\,mol^{-1}}$ .

Answer: 100

Numerical answer — enter this value.

\text{Mass\;of \;} \mathrm{H_2O} = 0.9\,\mathrm{g}

\text{Moles \;of \;} \mathrm{H_2O} = \frac{0.9}{18} = 0.05

\text{Moles \;of \;H} = 2 \times 0.05 = 0.10

\text{Mass\; of\; H} = 0.10\,\mathrm{g}

10\% \text{ H } \Rightarrow \text{mass\; of \;compound} = \frac{0.10}{0.10} = 1.0\,\mathrm{g}

\text{Molar \;mass\; of \;} X = \frac{1.0}{0.01} = 100\,\mathrm{g\,mol^{-1}}

Thus, the correct value is 100.

Answer key and solution verified before publishing.

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