A valency of a element is the measure of electrons it needs or needs to loose to obtain a stable structure (a noble gas structure,such as helium,neon,argon...)    
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The Brainliest Answer!
valency means combining capacity..
for example h₂o
here valency of hydrogen is 1 and valency of oxygen is 2.
because hydrogen combines with one atom of oxygen so valency of hydrozen is 1.
and oxygen combines with 2 atoms of hydrogen so valency of oxygen is 2.
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