Question

why do helium, argon, and neon have a zero valency?

Answer 1

Answer:

Because their octet or duplet are complete .that means they have 8 or 2(in case of helium only) are full.

So they are also inert because they gain/lose electrons.Thats why they are called noble gases

If you like my answer please mark me as brainliest. . .

Answer 2

Answer:

Helium, Argon and Neon because they are already stable and do not lose or gain any of their electrons.