The elements with the following atomic numbers belong to the same group:

In $s-$block,on moving down the group,the reactivity of metals with water and air increases. Which of the following factors has no significance for this trend of reactivity?

On moving down the group,which of the following properties gradually increases?

Identify the amphoteric oxide from the following.

The correct order of decreasing acidic nature of oxides is:

What is an amphoteric oxide?