NEET Questions Solved

NEET - 2006

In which of the following pairs are both the ions coloured in aqueous solution?

(a) Ni2+, Ti3+              (b) Sc3+, Ti3+

(c) Sc3+, Co2+            (d) Ni2+, Cu+

(At. no : Sc =21, Ti = 22, Ni = 28, Cu = 29, Co = 27)

(a) 28Ni = 1s2, 2s22p6, 3s23p63d8, 4s2

                          3d8

              

     Ni2+ = 1s2, 2s22p6, 3s23p63d8

     22Ti = 1s2, 2s22p6, 3s23p63d2, 4s2

       

    Ti3+ = 1s2, 2s22p6, 3s23p63d1

    21Sc = 1s2, 2s22p6, 3s23p63d1, 4s2

    Sc3+ = 1s2, 2s22p6, 3s23p6

 (unpaired electron in d-orbital is not possible)

    29Cu = 1s2, 2s22p6, 3s23p63d10, 4s1

       Cu+ = 1s2, 2s22p6, 3s23p63d10

                           (complete d-orbital)

 Hence, in above ions, Ni2+ and Ti3+ ions are coloured ions in aqueous solution due to presence of unpaired electrons in d-subshell.

 

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