The compound formed on heating chlorobenzene with chloral in the presence of concentrated sulphuric acid is

DDT

The answer is (2) DDT.

The compound formed on heating chlorobenzene with chloral in the presence of concentrated sulphuric acid is DDT.

The reaction is as follows:

DDT is an insecticide that was used extensively in the 20th century. However, it is now known to be harmful to the environment and to human health, and its use has been banned in many countries.

The other compounds in the answer choices are:

• Gammexane (hexachlorocyclohexane): an insecticide that is also known as lindane.
• Freon: a group of chlorofluorocarbons that are used as refrigerants and propellants.
• Hexachloroethane: a chlorinated hydrocarbon that is used as a fire retardant and insecticide.