Alkaline earth metals . have the smallest atomic radius in a given period form monoanions form basic oxides exist as triatomic molecules form halides with the formula MX

Alkaline earth metals form basic oxides.

Explanation:

Elements of group 2 are also known as alkaline earth metals. For example, Be, Mg, Ca, Sr, Ba and Ra are all group 2 elements.

Being placed on the left side of periodic table, alkaline earth metals have large atomic radius but their radius is smaller than alkali metals (group 1).

When oxygen combines with a metal then it results in the formation of a basic oxide.

For example, MgO is a basic oxide of group 2 element.

Thus, we can conclude that alkaline earth metals form basic oxides.

tracks, burrows, eggshells, nests, tooth marks, or gastroliths

the correct answer is:

a. formation of precipitation