i] Give a chemical test to distinguish between saturated and unsaturated hydrocarbon.
ii] Name the product formed when ethane burns is air. Write the balanced chemical equation for the reaction showing the types of energies liberated.
iii] Why is the reaction between methane and chlorine in the presence of sunlight considered a substitution reaction?

Explanation

(i) Pass the vapours of the given samples of saturated and unsaturated hydrocarbons into brumine water taken two separate test-tubes. The one which discharges the colour of bromine water is that of unsaturated hydrocarbon and other represents saturated hydrocarbon
(ii) On burning ethane in air, the products obtained are carbon dioxide and water, along with heat and light.
`2CH_(2)H_(6)(g) +70_(2)(g) rightarrow6H_(2)O(1)"+heat+Light"`
(iii) it is considered a substitution reaction because the hydrogen atoms of methane `(CH_(4))` are replaced by chlorine atoms one by one.