Which element has the ground state electronic configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s²?
This configuration (Z=28) corresponds to Ni (period 4, group 10), with 3d⁸ 4s², distinguishing it from Fe (3d⁶ 4s²), Co (3d⁷ 4s²), or Cu (3d¹⁰ 4s¹).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev