H4C2 is organic compound named 'Ethylene'! It contains two carbon atoms which have two hydrogen atoms bonded to each carbon! It is gas at room temperature!
h4c=four hydrogen and one carbon
Methane
Based on the naming rules for acids. This would be just hydrogen and carbon. H2C or H4C. BUT.. I do not know if this exists in nature, since carbon tends to form covalent bonds with hydrogen, not ionic. CH4 is methane, and CH2 is acetylene.