Question

why do Helium neon and Argon have a zero valency

Answer 1

here answer

hellium and neon atoms have 2 and 8 electrons respectively in their outermost shell, or the valence shell , and thus they are stable and would not take nor lose an electron
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Answer 2

HIi,, HERE IS YOUR ANSWER...

Helium Neon and Argon have 2,8 and 8 elections in their outermost orbit which is known as duplet or octet configuration and due to this they are stable and their all orbit have full with required electrons thus the valency of helium Neon and Argon is 0.

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