Question

what would a pentyne molecule look like

Answer 1

This is a bit ambiguous. It has a couple different appearances. you need to be more specific using IUPAC nomenclature.

Answer 2

Abb0t is right you need to specify the location of the triple bond on the molecule

Answer 3

Assuming that you want the simple structural formula of 1-pentyne or pent-1-yne it would be as follows . But as abbOt said, there are a lot of ways in which you could write it. You need to be more specific as to what you want.