Acetylene

ACETYLENE is a colorless gas with a faint garlic-like odor. Easily ignited and burns with a sooty flame. Gas is lighter than air. Flame may flash back to the source of a leak very easily. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

C2H2

HCCH

National Center for Biotechnology Information. PubChem Database. Acetylene, CID=6326, https://pubchem.ncbi.nlm.nih.gov/compound/Acetylene (accessed on May 27, 2019)