Organic Chemistry Basics 2 Question 16
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16. A gaseous hydrocarbon gives upon combustion $0.72 \mathrm{~g}$ of water and $3.08 \mathrm{~g}$ of $\mathrm{CO}_{2}$. The empirical formula of the hydrocarbon is
======= ####16. A gaseous hydrocarbon gives upon combustion $0.72 \mathrm{~g}$ of water and $3.08 \mathrm{~g}$ of $\mathrm{CO}_{2}$. The empirical formula of the hydrocarbon is
3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed (a) $\mathrm{C}{2} \mathrm{H}{4}$
(b) $\mathrm{C}{3} \mathrm{H}{4}$
(c) $\mathrm{C}{6} \mathrm{H}{5}$
(d) $\mathrm{C}{7} \mathrm{H}{8}$
(2013 Main)
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Answer:
Correct Answer: 16. (d)
Solution:
- $18 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}$ contains $2 \mathrm{~g} \mathrm{H}$
$$ \begin{aligned} & \therefore 0.72 \mathrm{~g} \mathrm{H}{2} \mathrm{O} \text { contains } 0.08 \mathrm{~g} \mathrm{H} \ & 44 \mathrm{~g} \mathrm{CO}{2} \text { contains } 12 \mathrm{~g} \mathrm{C} \ & \therefore \quad 3.08 \mathrm{~g} \mathrm{CO}_{2} \text { contains } 0.84 \mathrm{~g} \mathrm{C} \ & \therefore \quad \mathrm{C}: \mathrm{H}=\frac{0.84}{12}: \frac{0.08}{1} \ & =0.07: 0.08=7: 8 \end{aligned} $$
$\therefore$ Empirical formula $=\mathrm{C}{7} \mathrm{H}{8}$
