ANSWER is Xenon. Xenon(Xe) is a component of zero-valence elements called noble or INERT gases.It is inert to most normal chemical REACTIONS (e.g. combustion) since the outer valence shell contains eight electrons.This results in a stable, minimum energy configuration in which the outer electrons are tightly bound.The first published report confirming xenon anaesthesia was published in 1946 by the American medical researcher John H. Lawrence.Xenon has been undiscovered for a very long time, although it is present in traces in the ATMOSPHERE. It is still a subject of interest due to its reactivity with many elements in a specialised and regulated environment, hence the name "Stranger Gas."Neon is a chemical element with the Ne symbol and atomic number 10. It is a noble gas. Neon is a colourless, odourless, inert monatomic gas under normal conditions, with an air density of around two-thirds.Krypton is a chemical element with the Kr symbol and atomic number 36. It is a colourless, odourless, tasteless noble gas that exists in trace quantities in the atmosphere and is mostly used in fluorescent lamps with other rare gases.Argon is a chemical element with a symbol of Ar and an atomic number 18. It is a periodic table in group 18 and is a noble gas. Argon is the THIRD most abundant gas in the Earth's atmosphere, at 0.934 per cent (9340 ppmv).