JEE Main 2026 — Some Basic Concepts of Chemistry Question with Solution

Ratio of mass percentage of C : H = $12:1$

Ratio of moles of C : H = $\frac{12}{12}:\frac{1}{1}=1:1$

The empirical formula is $CH$. Since the hydrocarbon has two carbon atoms, its molecular formula is $C_2{H}_2$.

Molar mass of $C_2{H}_2=2\times 12+2\times 1=26$ g mol${}^{-1}$

Moles of $C_2{H}_2$ in $3.38$ g = $\frac{3.38}{26}=0.13$ mol

The combustion reaction is:

$C_2{H}_2+\frac{5}{2}{O}_2\to 2C{O}_2+H_{2}O$

From the stoichiometry, $1$ mole of $C_2{H}_2$ produces $2$ moles of $C{O}_2$.

Moles of $C{O}_2$ produced = $2\times 0.13=0.26$ mol

Molar mass of $C{O}_2=12+2\times 16=44$ g mol${}^{-1}$

Weight of $C{O}_2$ formed = $0.26\times 44=11.44$ g

Answer: $11.44$