Question

The empirical formula of a compound is $CH$. Its molecular weight is $78$. The molecular formula of compound will be

• A. $C_2{H}_2$
• B. $C_6{H}_6$
• C. $C_3{H}_3$
• D. $C_4{H}_4$

Answer 1

Answer: (B)

Molecular formula
$=(\text{ empirical formula }{)}_n$
$n=\frac{\text{ molecular weight }}{\text{ empirical formula weight }}$
$\because$ The empirical formula of compound $=CH$
$\therefore$ Empirical formula weight $=13$
Molecular weight $=78$
$n=\frac{78}{13}=6$
Hence, molecular formula
$=(\text{ empirical formula }{)}_n$
$=(CH{)}_6=C_6{H}_6$