# What is an unsaturated hydrocarbon with a triple bond and two carbons?

$\text{An alkyne...........}$
And the simplest alkyne is $\text{acetylene}$, $H - C \equiv C - H$; this has two degrees of unsaturation; i.e. there are 4 hydrogens less than the corresponding alkane formula, that of ethane, ${C}_{2} {H}_{6}$.