From the following identify the groups that exhibit negative resonance (-R) effect when attached to conjugated system \(\begin{array}{ccccc} \text { formyl } & \text { amino } & \text { alkoxy } & \text { cyano } & \text { nitro } \\ \text { A } & \text { B } & \text { C } & \text { D } & \text { E } \end{array}\)

• A

  A, C, E only
• B

  B, C, D only
• Correct answer
  C

  A, D, E only
• D

  B, D, E only

Solution

Negative Resonance (-R): A group which withdraw electron density from a conjugated system.
$\begin{aligned} & \text { Amino } \rightarrow \mathrm{NH}_2 \rightarrow+\mathrm{R} \\ & \text { Alkoxy } \rightarrow-\mathrm{OR} \rightarrow+\mathrm{R}\end{aligned}$ $\begin{aligned} & \text { Cyano } \rightarrow-\mathrm{CN} \rightarrow-\mathrm{R} \\ & \text { Nitro } \rightarrow-\mathrm{NO}_2 \rightarrow-\mathrm{R}\end{aligned}$ $\therefore \mathrm{A}, \mathrm{D}, \mathrm{E}$ group show -R effect.

Hence, the correct answer is option: 'C'.