Question

why helium have zero valency​

Answer 1

Explanation:

It is so because it's atomic number is 2 and it donet this 2 electrons to its outermost shell which is K shell and the capacity of K shell is of 2 so it is satisfied.

0 electrons are remaining for loosing and K shell means outermost shell is sataisfied therefore it's valency is 0

Answer 2

Here is Your Answer :-

—> Helium is a Noble Gas Element.
—> It’s Configuration is 1s2.
—> Generally Noble Gases have Stable Configuration...
—> So they don’t react to any element..
—> So, Helium as well as all Noble Gas Elements Don’t Have Valence Shells...ie., Valency.

Hope it Helps You..