Answer: raregas

AnswerCrossword Clue
RAREGAS

Xenon or krypton

RAREGAS

Krypton, for one

RAREGAS

Xenon, for one

RAREGAS
Argon or xenon
RAREGAS
Argon or xenon, say
RAREGASNeon or argon
RAREGASNeon, for one
RAREGASXenon, e.g.
RAREGASErstwhile name for a "noble" element
RAREGASNoble element
RAREGASKrypton, e.g.
RAREGASIt doesn't react very well
RAREGASNoble one
RAREGASNeon, e.g.
RAREGASLast-column element on the periodic table
RAREGASOne highly unlikely to react
RAREGASNoble at the end of a table?