Question

With respect to the compounds I-V, choose the correct statement(s).

• A. The acidity of compound $I$ is due to delocalization in the conjugate base
• B. The conjugate base of compound IV is aromatic
• C. Compound II becomes more acidic, when it has a $- NO _{2}$ substituent
• D. The acidity of compounds follows the order $| > | V > V > II > III $

Answer 1

Answer: (A), (B), (C)

Triphenylmethane $(I)$ is acidic because its conjugate base is stabilised by resonance.
Cyclopentadiene $(IV)$ is acidic because its conjugate base is aromatic.
Nitrobenzene is more acidic than benzene because nitro group is electron withdrawing. It will stabilise the conjugate base of benzene by - $I$ effect.
The correct order of acidity of the given compounds is $IV > V > I > II > III$.