Two Atoms of This Plus an Oxygen Atom Makes Water
This page is the CodyCross answer for the clue below from Prehistory, Group 1244, Puzzle 3 (Spears and Arrows).
Question is: Two Atoms of This Plus an Oxygen Atom Makes Water
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.