90% of Jupiter's Atmosphere Is Made Up of This Gas
This page is the CodyCross answer for the clue below from The Netherlands, Group 2115, Puzzle 4 (Almere and Nijmegen).
Question is: 90% of Jupiter's Atmosphere Is Made Up of This Gas
and the answer is: HYDROGEN
Word Meaning:
HYDROGEN — (uncountable) The lightest chemical element (symbol H), with an atomic number of 1 and atomic weight of 1.008.
Definitions from Wiktionary.