Which of the following is the electron configuration of an electrically neutral alkaline earth metal

A. 1s2 2s1

B. 1s2 2s2 2p2

C. 1s2 2s2 2p6 3s1

D. 1s2 2s2 2p6 3s2 3p6 4s2

I feel like the answer is D, but I'm not sure.

Option d, 1s2 2s2 2p6 3s2 3p6 4s2

Explanation:

Alkaline earth metals belong to group 2 of the periodic table. Elements belonging to group 2 are beryllium, magnesium, calcium, strontium and barium and radium.

Alkaline earth metals have 2 valence electrons and these two electrons are filled in outermost s sub shell.

General electronic configuration of alkaline earth metal: ns^2

In ionized state, number of electrons in s sub shell will not be 2.

Among the given, only 1s2 2s2 2p6 3s2 3p6 4s2, has 2 electrons in s sub shell. So, it an electronic configuration of neutral alkaline earth metal.

I believe the answer is A.