Question

Why do the elements helium ,neon and argon have zero valency?

Answer 1

because helium , neon n argon have a completely filled outer shell n thus require no 
extra electrons. this is also the reason why they were discovered so late.
plz mark brainliest

Answer 2

element configuration
K L M N
2. 8. 8. 2.
helium. 2
Neon. 2. 8.
Argon. 2. 8. 8.
now here these elements have completely filled shells..
they don't need any more electron that's why there valence is zero....