Question

Alkaline earth (group 2 or IIA elements) differ from group 12 (or IIB) elements in the electronic configuration of their:

• A. Anitipenultimate shell
• B. Innermost shell
• C. Outermost shell
• D. Penultimate shell

Answer 1

The correct option is D Penultimate shell

Electronic configuration Alkaline earth (group 2 or IIA elements) is $n{s}^2$
Electronic configuration group 12 (or IIB) elements is $n{s}^2,(n-1)d^{10}$,
so these twogroups differ in their electronic configaration of penultimate shell.
Hence option D is correct.