(i) Give a kherical test to distinguish between saturated and unsaturated hydrocarbons.
(ii) Name the products fornted when ethanol burns in air. List two forms of energy that are liberated on burning ethanol.
(iii) Why is the reaction between methane and chlorine considered a substitution reaction?

Explanation

(i) Saturated hydrocarbons burn with clean flame and do not decolourise brown colour of bromine, Unsaturated hydrocarbons burn with sooty flame and decolourise brown colour of bromine.
(ii) Ethanol burns in air to form carbon dioxide and water.
`CH_(3)CH_(2)OH + 3O_(2) rightarrow 2CO_(2) + 3H_(2)O`
(iii) Reaction between methane and chlorine is considered a substitution reaction because one atom of hydrogen from methane is replaced by one atom of chlorine and forms chloromethane.