Question

Except which gas all other noble gases have octet in their valence shell?

Answer 1

Noble gases, any of the seven chemical components that make up Group $18$ ($VIIIa$) of the periodic table. The components are helium ($He$), neon ($Ne$), argon ($Ar$), krypton ($Kr$), xenon ($Xe$), radon ($Rn$), and oganesson ($Og$). The noble gases are colorless, unscented, tasteless, nonflammable gases.

Complete step-by-step answer: Noble gases generally have been marked Group $0$ in the periodic table in light of the fact that for quite a long time after their disclosure it was accepted that they couldn't attach to different molecules; that will be, that their particles couldn't consolidate with those of different components to frame chemical components. Their electronic structures and the finding that some of them do in fact frame compounds has prompted the more proper designation, Group$18$.
The octet rule is a general guideline for chemicals that mirrors the hypothesis that fundamental group components will, in general, tend to bond in such a way so that every particle has eight electrons in its valence shell, giving it a similar electronic arrangement as a noble gas. The rule is particularly appropriate to carbon, nitrogen, oxygen, and the halogens, yet additionally to metals, for example, sodium or magnesium.
Aside from helium gas, any remaining noble gases have octet in their valence shell. Helium has an electronic arrangement:$1{s^2}$. Consequently, it doesn't include an octet in its arrangement. It is a dreary, tasteless, unscented, non-harmful, monoatomic gas. It has a boiling point, the least of all the relative multitude of other components.

Note: The chemical behavior of the fundamental group components can be anticipated with the assistance of the octet rule. This is on the grounds that the standard just includes $s$ and $p$ electrons, where the octet relates to an electron arrangement finishing with${s^2}{p^6}$. These components will in general shape bonds to acquire stable octet setups.