Here's why:

* Ethyne is the IUPAC name for the compound with the formula C₂H₂.

* Acetylene is the common name for the same compound.

* C₂H₂ is the molecular formula, indicating two carbon atoms and two hydrogen atoms.

The structure of ethyne features a triple bond between the two carbon atoms. This triple bond gives the molecule its unique properties, including its high reactivity and its use in welding and cutting torches.