Question

what is variable valency? why it occurs ​

Answer 1

The combining capacity of an atom. Is known as valency.

Answer 2

Answer:

Some elements differ in their capacity to combine with other elements depending on the nature of the reaction; this property is called variable valency.

Explanation:

They occurs because the electrons present in the outermost shell of an atom are called valence electrons. If the valency electrons are removed, the remainder is called Core.