Question

$74$ g of a compound on complete combustion gives $132$ g $C{O}_2$ and $54$ g of $H_{2}O$. The molecular formula of the compound may be :

• A. $C_5{H}_{12}$
• B. $C_4{H}_{10}O$
• C. $C_3{H}_6{O}_2$
• D. $C_3{H}_7{O}_2$

Answer 1

Answer: (C)

$C_3{H}_6{O}_2$

$74$ g of a compound on complete combustion gives $132$ g $C{O}_2$ and $54$ g of $H_{2}O$.
This corresponds to $\frac{132}{44}=3$ moles of $C{O}_2$ and $\frac{54}{18}=3$ moles of $H_{2}O$.
Thus, one molecule of organic compound contains $3$ carbon atoms and $6$ hydrogen atoms.
The molecular formula of the compound may be $C_3{H}_6{O}_2$.