Question

what is valancy?????

Answer 1

In chemistry, the valence or valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules. The concept of valence developed in the second half of the 19th century and helped successfully explain the molecular structure of inorganic and organic compounds. Wikipedia
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Answer 2

Gain or loss of electrons to complete octate rule is called valency.
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