Question

Which species are more resonance stabilized in the following pairs:
`[C_(6)H_(5)Cl, C_(6)H_(5)CH_(3)], [CH_(2)=CHCl, CH_(2)=CHCH_(2)Cl]`,
`[C_(6)H_(5)Br, C_(6)H_(5)CH_(2)Br], [CH_(3)COOH, CH_(3)COO^(-)]`
A. `C_(6)H_(5)Cl, CH_(2)=CHCH_(2)Cl, C_(6)H_(5)CH_(2)Br, CH_(3)COO^(-)`
B. `C_(6)H_(5)CH_(3), CH_(2)=CHCH_(2)Cl, C_(6)H_(5)CH_(2)Br, CH_(3)COO^(-)`
C. `C_(6)H_(5)C1, CH_(2)=CHCl, C_(6)H_(5)Br, CH_(3)COOH`
D. `C_(6)H_(5)Cl, CH_(2)=CHCl, C_(6)H_(5)Br, CH_(3)COO^(-)`

Answer 1

Correct Answer - D
In the first pair, `-Cl` has stronger `+R` effect than `CH_(3)` in the second pair, `Cl` lone pair is in conjugation with double bond, in the third pair, `Br` lone pair is in conjugation with benzene ring, in the fourth pair, `CH_(3)COO^(-)` is more resonace stabilizeed due to equivalent resonating structures.