MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The electronic configuration of Fe (Z=26) is [ Ar ] 3d^6 4s^2. The electronic configuration of Fe ^ 2+ is [ Ar ] 3d^6. It has 4 unpaired electrons. The electronic configuration of Mn (Z=25) is [ Ar ] 3d^5 4s^2. The electronic configuration of Mn ^ 2+ is [ Ar ] 3d^5. It has 5 unpaired electrons. The electronic configuration of Co (Z=27) is [ Ar ] 3d^7 4s^2. The electronic configuration of Co ^ 2+ is [ Ar ] 3d^7. It has 3 unpaired electrons. The electronic configuration of Ni (Z=28) is [ Ar ] 3d^8 4s^2. The electronic configuration of Ni ^ 2+ is [ Ar ] 3d^8. It has 2 unpaired electrons. The electronic configuration of Cr (Z=24) is [ Ar ] 3d^5 4s^1. The electronic configuration of Cr ^ 2+ is [ Ar ] 3d^4. It has 4 unpaired electrons. Thus, Fe ^ 2+ and Cr ^ 2+ both have 4 unpaired electrons. Answer: Fe ^ 2+ and Cr ^ 2+