4. Elements belonging to the same group have the same valency.

Ans. 1. The valency of an element is determined by the number of valence electrons present in the outermost shell of an atom.

2. The electronic configuration of the outermost shell is same for all the elements belonging to the same group.

3. So, the number of valence electrons for all the elements in a group is the same.

4. Therefore, elements belonging to the same group have the same valency.