Question

Which of the following is an alkaline earth metal?

• A. ${}_{11}$Na
• B. ${}_{12}$Mg
• C. ${}_{19}$K
• D. ${}_{13}$Al

Answer 1

The correct option is B ${}_{12}$Mg

Alkaline earth elements are elements found in the second group of the periodic table. These elements have two valence electrons.
In the given options magnesium $\text{(Mg)}$ is the only element having two valence electrons. So it belongs to the second group and is an alkaline earth metal.