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JEE MAIN 2021
20-07-21 S2
Question
An aqueous solution of $\mathrm{NiCl}_2$ was heated with excess sodium cyanide in presence of strong oxidizing agent to form $\left[\mathrm{Ni}(\mathrm{CN})_6\right]^{2-}$. The total change in number of unpaired electrons on metal centre is $\_\_\_\_$ .
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