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NEET2018Chemistryd and f Block ElementsActual

Which is least stable in aqueous medium?

Options

  1. AFe ²⁺
  2. BCo ²⁺
  3. CNi ²⁺
  4. DMn ²⁺

Correct answer

A. Fe ²⁺

Step-by-step solution

Fe ²⁺ (3 d^6 ) quickly oxidises to Fe ³⁺ (3 d^5 . , more stable) in aqueous medium.

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