NEET levelSingle correct optionDifficulty 1 of 3g1222
In the ion shown, over which atoms is the negative charge delocalised through resonance?
Athe oxygen atom only
Bthe terminal carbon only
Cthe oxygen and the terminal carbon
Dthe oxygen and both carbon atoms
Answer: C
The ion shown is the enolate of acetaldehyde. The lone pair on oxygen can move in to form a C=O bond while the C=C pi electrons move onto the terminal carbon. Hence the charge is shared by oxygen and the terminal carbon.