Question

Name two elements having variable valency and state their valencies.
pls help me from book
Concise Chemistry Book name
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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

Valency of an element is decided by numer of outermost shell electrons. If an element exhibit more than one valency . This is known as variable valency.

example, copper, tin, iron and mercury