What are neon, argon, xenon and krypton?
Xenon krypton/xenon mixture may be separated into krypton and xenon by further distillation. Worldwide production of xenon in 1998 was estimated at 5,000–7,000 m. Because of its scarcity, xenon is much more expensive than the lighter noble gases—approximate prices for the purchase of small quantities in Europe in 1999 were 10 €/L for xenon, 1 €/L for krypton, and 0.20 €/L for neon, while the much more plentiful argon costs less than a cent per liter. Within the Solar System, the nucleon fraction of xenon is , for an abundance of approximately one part in 630 thousand of the total mass.
Argon argon was "A", but now is "Ar". Argon constitutes 0.934% by volume and 1.288% by mass of the Earth's atmosphere, and air is the primary industrial source of purified argon products. Argon is isolated from air by fractionation, most commonly by cryogenic fractional distillation, a process that also produces purified nitrogen, oxygen, neon, krypton and xenon. The Earth's crust and seawater contain 1.2 ppm and 0.45 ppm of argon, respectively. The main isotopes of argon found on Earth are (99.6%), (0.34%), and (0.06%). Naturally occurring , with a half-life of 1.25 years, decays to stable (11.2%) by electron capture or