Remember, we define x and Y to be any compound, molecule or atom that is different than H. And that means our x and Y are both heavier than H's. So this compound is one isomer of this molecular formula and it's the sys or Z isomer. What about trans or e? Well, let's recall another important detail about alkenes. Alkines have double bonds, and that means we can't rotate this molecule. The only way we rotate this lower bond is if we break the Pi bond.