Question

An aromatic hydrocarbon with empirical formula $ {{C}_{5}}{{H}_{4}} $ on treatment with concentrated $ {{H}_{2}}S{{O}_{4}} $ gave a monosulphonic acid. $ 0.104 \,g $ of the acid required $ 10 \,mL $ of $ \frac{N}{20}NaOH $ for complete neutralization. The molecular formula of hydrocarbon is

• A. $ {{C}_{5}}{{H}_{4}} $
• B. $ {{C}_{10}}{{H}_{8}} $
• C. $ {{C}_{15}}{{H}_{12}} $
• D. $ {{C}_{20}}{{H}_{16}} $
• E. $ {{C}_{15}}{{H}_{20}} $

Answer 1

Answer: (C)

Empirical formula $ ({{C}_{5}}{{H}_{4}})+{{H}_{2}}S{{O}_{4}}\to $
Monosulphonic acid
$ 0.104\, g $ of acid required $ 10\, mL $ of
$ \frac{N}{20}NaOH $ for completely neutralization
$ \frac{0.104}{n(5\times 12+4\times 1)}=\frac{1}{20}\times 10\times {{10}^{-3}} $
$ n=\frac{104}{32}=3.25\approx 3 $
The molecular formula of hydrocarbon will be C is $ {{C}_{15}}{{H}_{12}} $ .