Question

A hydrocarbon C2H4 decolourise bromine water.
(a):- Name the hydrocarbon

Answer 1

The hydrocarbon is ethene

Answer 2

The hydrocarbon is of form CnH2n, so it is an alkene. Namely, as it contains two carbon atoms, it is Ethene. It has a double bond which is an unsaturation. Bromine water is generally brown in colour, so when it is added to Ethene, bromine gets doubly substituted across the double bond, so the bromine water gets deoclourized.