Gas Used in Respiration, Atomic Number 8
Puzzle 15 of Periodic Table Medium Pack
Question is: Gas Used in Respiration, Atomic Number 8
and the answer is: OXYGEN
Word Meaning:
OXYGEN — The chemical element (symbol O) with an atomic number of 8 and relative atomic mass of 15.9994. It is a colorless and odorless gas. Sometimes called elemental oxygen to distinguish it from molecular oxygen.
Definitions from Wiktionary.