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The valency of an element is a measures  of its combining capacity ............. e.g  as atomic  no . of hydrogen is 1 or of boron is 5 in the 1st orbit of netrons is 2 so we will take 2 in the 1st place & the remaining will be in the 2nd place so the remaing value of boron is 3 so valency is 3 ..... boron5 -2,3 v.3
1 5 1
The valency of an element is the number of hydrogen atoms that can combine with or replace one atom  of the element.
example:valency of hydrogen is 1.
2 4 2