Unsaturated hydrocarbons contain multiple bonds between the two C-atoms and show addition reaction. Give the test to distinguish ethane from ethene.

Explanation

Ethane is unsaturated hydrocarbon as it contains a double covalent bond between two carbon atoms. Presence of unsaturated or double covalent bond can be distinguished with the help of bromine solution in `C Cl_(4)` .It is an orange colour solution which shows colour change after addition in ethane solution.
The orange colour disapperars because of formation of the colourless ethylene dibromide.
`(CH_(2)Br-CH_(2)Br)`.
It is addition reaction of ethence due to presence of double covalent bond in the molecule .
`CH_(2)=CH_(2)+Br_(2)toCH_(2)Br-CH_(2)Br`
Ethane is a saturated hydrocarbon and cannot show this test .It burns with a clear flame whereas unsaturated hydrocarbons burn with yellow flame and lots of black smoke .