What is the test for the presence of unsaturated bonds?
The standard test would be the decolourization of bromine water.
As an olefin, of course cyclopentene should undergo this reaction; cyclopentane should be inert.
As a tip, when you do these things in the lab, it is always a good idea to perform the test on a reagent whose identity you know. For instance, for this test, take actual hexene, add a little bromine water, and see how it decolourizes. And this way we can see the results of a positive text, and compare these results with those obtained from an unknown chemical.