Which of the following groups in the periodic

table contain elements so reactive that they are

never found in the free state?

(1) 1 and 2

(3) 2 and 15

(2) 1 and 11

(4) 11 and 15

Elements of Group 1 and group 2 in the periodic table contain elements so reactive that they are never found in the free state

Explanation:

The metals in group 1 of periodic table consisting of 'alkali metals' which include lithium, potassium, sodium, rubidium, Francium and caesium. They are highly reactive because they have low ionisation energy and larger radius. The group 2 metals consist of 'alkaline earth metals' which include calcium, strontium, barium, beryllium, radium and magnesium. These alkaline earth metal have + 2 oxidation number, hence are highly reactive.

These both group metals are mostly reactive and so are never found in a free state. When they are exposed to air they would immediately react with oxygen. Hence, are stored in oils to avoid oxidation.