Question

in group valency number of number of valence electrons​

Answer 1

Answer:

As we move from top to bottom in a group, the number of valence electrons remains same because a group is defined such that their valence shell configuration is same. Hence, valence electrons remain same but valence shell changes.

Answer 2

Answer:

An atom with one or two valence electrons more than a closed shell is highly reactive, because the extra valence electrons are easily removed to form a positive ion.