Question

what do helium, neon and argon have a zero valency

Answer 1

Helium neon and Argon have zero valency because in because in the last shell their is no electron is left and they are stable

Answer 2

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Helium has two electrons in its only energy shell. ... As the elements have the maximum number of electrons in their valence shells (thereby achieving stable duplet and octet configurations), they do not have any tendency to combine with other elements. Hence, Helium, Neon, and Argon have zero valency.