Gas Used to Help Balloons Float
This page is the CodyCross answer for the clue below from Greece, Group 676, Puzzle 3 (The Underworld).
Question is: Gas Used to Help Balloons Float
and the answer is: HELIUM
Word Meaning:
HELIUM — (uncountable) The second-lightest chemical element (symbol He), with an atomic number of 2 and atomic weight of 4.002602, a colorless, odorless and inert noble gas.
Definitions from Wiktionary.