2024 · Q20
Match List I with List II and select the correct answer using the code given below the Lists:
List I (Element):
- ABoron,
- BNitrogen,
- COxygen,
- DNeon
List II (Unpaired electron):
- 1Zero,
- 2Two,
- 3One,
- 4Three
general-sciencechemistry
- AA-1, B-4, C-2, D-3
- BA-1, B-2, C-4, D-3
- CA-3, B-2, C-4, D-1
- DA-3, B-4, C-2, D-1
Explanation
Using Hund's rule: boron (Z=5, 1s2 2s2 2p1) has one unpaired electron, so A matches 3. Nitrogen (Z=7, 1s2 2s2 2p3) has three unpaired electrons, so B matches 4. Oxygen (Z=8, 1s2 2s2 2p4) has two unpaired electrons, so C matches 2. Neon (Z=10, 1s2 2s2 2p6) has a filled shell with zero unpaired electrons, so D matches 1. The correct code is A-3, B-4, C-2, D-1.