Question

Which of the following transition metal catios have noble gas core?
(a) `Sc^(3+)` (b) `Y^(3+)`
(c) `La^(3+)` (d) `Ac^(3+)`
A. (i), (ii), (iii)
B. (i), (ii), (iii), (iv)
C. (i), (ii), (iv)
D. (ii), (iii), (iv)

Answer 1

Correct Answer - B
After obtaining the electron configuration of the atom (using the building-up principle), remove ns electrons, then `(n-1)d` electrons, until we have the correct positive charge on the ion, e.g., `Sc([Ar]3d^14s^2)rarrSc^(3+)[Ar],Y([Kr]4d^15s^2)rarrY^(3+)([Kr])`