Question

what is variable velency ​

Answer 1

Answer:

Certain elements have more than one valency. They exhibit variable valency. For example, copper, tin, iron and mercury exhibit variable valency. Copper combines with oxygen to form cuprous oxide (Cu2O) and cupric oxide (CuO).

Answer 2

Answer:

Some elements vary in their ability to interact with other elements, depending on the nature of the reaction; variable valence is called this property. Iron (Fe), for example, may have a valence of both 2 and 3