Question

 Give a test that can be used to differentiate chemically between butter and cooking oil.

Give a test that can be used to differentiate between saturated and unsaturated hydrocarbons.

Answer 1

Bromine water test can be used to chemically differentiate between a butter (Saturated) and cooking oil (Unsaturated).
Take two test tubes, one with a small amount of butter in it and the other with some cooking oil. 
Add bromine water to both the test tubes.
Observation:
(1) Cooking oil decolourises bromine water indicating that it is an unsaturated compound.
(2) Butter does not decolourise bromine water indicating that it is a saturated compound.