• # question_answer When $Ca{{C}_{2}}$is hydrolysed it produces a gas which when treated with red hot tube it produces an organic compound A which on reaction with excess of $C{{l}_{2}}$ produces a chemical compound which is used to kill insecticide [B]. Identify B A)  benzene                                      B)  BHC (Benzene Hexa Chloride) C)  chloro benzene         D)  trichloro benzene

Idea This problem includes conceptual mixing of preparation, properties of benzene and application of compound of benzene. Students are advised to complete chemical reaction and understand use of compound obtained after reaction. Preparation of benzene When calcium carbide is hydrolysed it produce acetylene .gas which on heated with Fe or Cu at $500{}^\circ C$ produces benzene. Properties of benzene Benzene on treated with excess of $C{{l}_{2}}$ produces gammexane or benzene hexachloride (BHC) which is used as an insecticide. Test Edge Problems related various other antioxidant such as BHT, are also asked frequently. Students are advised to undergo preparation and properties of such useful chemicals.