Consider the following statements about some polyhalogen compounds.
(A) Freons are extremely stable, unreactive, non-toxic, non-corrosive and easily liquefiable gases.
(B) Freon 12 (CCl2F2) is manufactured from tetrachloromethane by the Finkelstein reaction.
(C) The major use of chloroform today is in the production of the freon refrigerant R-22.
(D) In the stratosphere, freon is able to initiate radical chain reactions that can upset the natural ozone balance.
Which of the statements given above are correct? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (C) and (D) only
Freons are the chlorofluorocarbon compounds of methane and ethane. They are useful because they are so stable, and harmful for the same reason: they last long enough to reach the stratosphere.
(A) Freons are extremely stable, unreactive, non-toxic, non-corrosive and easily liquefiable gases. — True. These properties make them suitable as aerosol propellants and refrigerants.
(B) Freon 12 (CCl2F2) is manufactured from tetrachloromethane by the Finkelstein reaction. — False. Freon 12 is made by the Swarts reaction, in which chlorine is exchanged for fluorine using a metallic fluoride. The Finkelstein reaction puts iodine in place of Cl or Br, using NaI in dry acetone.
(C) The major use of chloroform today is in the production of the freon refrigerant R-22. — True. Chloroform was once a general anaesthetic, but today it is used mainly to make R-22, and also as a solvent.
(D) In the stratosphere, freon is able to initiate radical chain reactions that can upset the natural ozone balance. — True. Most freon diffuses unchanged into the stratosphere, where it starts radical chain reactions that disturb the ozone balance.
NCERT (2026-27 edition):
6.8.5 Freons – “The chlorofluorocarbon compounds of methane and ethane are collectively known as freons. They are extremely stable, unreactive, non-toxic, non- corrosive and easily liquefiable gases. Freon 12 (CCl2F2) is one of the most common freons in industrial use. It is manufactured from tetrachloromethane by Swarts reaction.” … “In stratosphere, freon is able to initiate radical chain reactions that can upset the natural ozone balance.”
6.8.2 Trichloromethane (Chloroform) – “…The major use of chloroform today is in the production of the freon refrigerant R-22.”