Which reagent can be used to identify `Ni^(2+)` ion ?

Explanation

For `Ni^(2+)= 3d^(8) = ` ` (##PR_CHE_V01_XII_C08_E09_026_S01.png" width="80%"> . Hence,`n=2 ,=sqrt(n(n+2))= sqrt(2(2+2))= sqrt(8)=2.84BM.`