You can use Baeyer's test.
Baeyer's test is used to detect the presence of unsaturation in organic compounds specifically for alkenes and alkynes. This uses a cold dilute neutral aqueous solution of
The presence of unsaturation will be indicated by the loss of purple color of the the potassium permanganate solution and formation of a brown precipitate due to the formation of
In your problem, propene will give a positive result since there is a presence of