Write a test to detect the presence of double bond in a molecule.

Explanation

The presence of double bond (i.e., unsaturation) in a molecule can be detected by the followin two tests. (i) `Br_(2)` in `C Cl_(4)` test. When `Br_(2)//C Cl_(4)` is added to the solution of an unsaturated compound in `C Cl_(4)`, the orange colour of `Br_(2)` disappears due to the formation of colourless dibromo compound.

(ii) Baeyer's test. when a cold aqueous alkaline solution of `KMnO_(4)` is added to the aqueous solution or suspension of an unsaturated compound, the pink colour of `KMnO_(4)` solution gets discharged due tot he formation of the corresponding 1,2-dihydroxy compound or 1,2-glycol.