Question

Helium is a non reactive gas and neon is a gas of extremely low reactivity. what ,if anything, do their atoms have in common?

Answer 1

Helium has an outer electron shell of only 2 electrons Neon has outer shells of 8 electrons all three have filled outer shells and are unusually stable.

Answer 2

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1) It belongs to the last group with all the gas whose last shell are common and they are unreactive unlike to other elements which reacts to complete their last shell with total 8 electrons .

2) Helium and Neon have in common that they have their shell complete and they reacts very less or they don't.