1. Intramolecular hydrogen bonding occurs when a hydrogen atom forms a bond within the same molecule between a donor (e.g., OH, NH) and an acceptor (e.g., $NO_2$, CO).
2. Option (4) has OH and $NO_2$ groups in close proximity, allowing intramolecular hydrogen bonding.
3. The other options lack this spatial arrangement.
List I | List II | ||
---|---|---|---|
A | Mesozoic Era | I | Lower invertebrates |
B | Proterozoic Era | II | Fish & Amphibia |
C | Cenozoic Era | III | Birds & Reptiles |
D | Paleozoic Era | IV | Mammals |