MHT CET Chemistry Question (2026) — Solution

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The electronic configuration of Lutetium (Lu), which has an atomic number of 71, is [ Xe ] 4f^ 14 5d^ 1 6s^ 2 . In the +3 oxidation state, Lu loses two electrons from the 6s orbital and one electron from the 5d orbital. Therefore, the electronic configuration of Lu ^ 3+ is [ Xe ] 4f^ 14 . For the other given elements in their +3 state: Tm ^ 3+ (Z=69) has the configuration [ Xe ] 4f^ 12 . Ce ^ 3+ (Z=58) has the configuration [ Xe ] 4f^ 1 . Dy ^ 3+ (Z=66) has the configuration [ Xe ] 4f^ 9 . Answer: Lu