Question

List the following compouns from highest to lowest frequency.
Cyclohexanone, 2-cyclohexenone, cyclohexanecarbaldehyde

Answer 1

What do you mean by the frequency of a compound?

Answer 2

Probably you are referring either to the frequency of the absorbing groups for infrared spectroscopy or for NMR. In either case, however, just look up the frequencies in a table and rank them yourself.