Question

what are the importance and variable valency​

Answer 1

Valency determines the chemical property of an element.

Also it gives us account whether an element is a metal or non metal

Answer 2

ʜᴏʟᴀ ᴍᴀᴛᴇ !

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⭐ᴀɴsᴡᴇʀ⭐

Certain elements combine with other atoms, donating, accepting or sharing electrons in different proportions depending on the nature of the reaction. For example, iron combines with oxygen to form ferrous oxide as well as ferric oxide. This is termed variable valency.