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julietwin1
They have 2 valence electrons. A tip my Chemistry teacher gives is to look at the number of the group (A groups) because, the number of the group generally correlates to the number of valence electrons within that group.

Answer: Option (a) is the correct answer.

Explanation:

General electronic configuration of group 2 elements is [tex]ns^{2}[/tex]. And valence electrons are the electrons present in outermost shell of an atom.

For example, magnesium is a group 2 elements and has electronic configuration [tex]1s^{2}2s^{2}2p^{6}3s^{2}[/tex].

Thus, we can see that there are 2 electrons in the outermost shell of group 2 elements.

Hence, we can conclude that the elements in group 2 all have 2 valence electrons.

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