Question

can the valency of an element be variable ? if it can mention two such elements and show that how they form compounds.How are these compounds named

Answer 1

yes it is possible. For Copper it's valencies are 1 and 2. For gold 1 and 3. CuCl named as cuprous chloride and CuCl 2 named as cupric chloride

Answer 2

ANSWER

This picture is your answer i have mention it very nicely.