Question

The valence electronic configuration of an atom is $6s^2$. If d orbital of the penultimate shell contains two unpaired electrons, calculate the atomic number

• A. 72
• B. 48
• C. 76
• D. 58

Answer 1

Answer: (A)

72

The electronic configuration of the atom can be written as:
$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}4d^{10}4f^{14}5s^{2}5p^{6}5d^{2}6s^2$
Thus the atomic number is 72.