Question

A hydrocarbon contains 7.70% hydrogen. 0.56L of the hydrocarbon weighs 1.95g at STP. Then hydrocarbon is an

• A. Alkane
• B. alkene
• C. alkyne
• D. arene

Answer 1

The correct option is D

arene

Arene
$\begin{array}{ccccc}Elements& \%& AtWt& \%& Ratio\\ C& 92.3& 12& 7.66& 1\\ H& 7.70& 1& 7.7& 1\end{array}$
Empirical formula = CH
22.4L at STP weight $=\frac{1.95}{0.56}\times 22.4=78$
$\therefore$ molar mass =78
Formula $=C_6{H}_6$ i.e. it is an arene