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MHT CET202618 April 2026Evening ShiftChemistryd and f Block ElementsActual

Which from following pair of elements in their respective oxidation states have same number of unpaired electrons ?

Options

  1. AFe ²⁺ and Mn ²⁺
  2. BCo ²⁺ and Ni ²⁺
  3. CFe ²⁺ and Cr ²⁺
  4. DCo ²⁺ and Fe ²⁺

Correct answer

C. Fe ²⁺ and Cr ²⁺

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

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