Question

How there are multiple valency of some elements

Answer 1

Answer:

some elements show the tendency to show multiple valencies on the account of inert pair effect which increases on moving down a particular group due to shielding effect caused by the electrons present in the orbitals inner to the orbital containing valence electron.However, out of the different valencies shown by the element, only one valency is stable and that depends in inert pair effect.

Answer 2

Answer:

Explanation:

Sometimes, the same element may have one valency in a compound and another valency in other compound. An atom of an element can sometimes lose more electrons than are present in its valence shell i.e. loss from the penultimate shell or vacant orbitals and hence have more than 1 or variable valency.