Match List-I with List-II
| List-I Polyhalogen Compound | List-II Applications |
| (A) Iodoform | (I) propellants for aerosol cans |
| (B) DDT | (II) Antiseptic |
| (C) Trichloromethane | (III) Insecticide |
| (D) Tetrachloromethane | (IV) Freon refrigerant R-22 |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A) - (II), (B) - (III), (C) - (IV), (D) - (I)
Polyhalogen compounds carry more than one halogen atom. Many are useful in industry and agriculture, but several are now restricted because they are toxic or harm the environment.
(A) Iodoform — This matches (II) Antiseptic. \( \ce{CHI3} \) was once used as an antiseptic; its action is due to the free iodine it releases, not to iodoform itself. Its objectionable smell led to its replacement.
(B) DDT — This matches (III) Insecticide. DDT (p,p′-dichlorodiphenyltrichloroethane) was the first chlorinated organic insecticide, used against the mosquitoes that spread malaria and the lice that carry typhus. It is not easily metabolised and is stored in fatty tissue, so it is now banned in many countries.
(C) Trichloromethane — This matches (IV) Freon refrigerant R-22. Chloroform is used to make the refrigerant R-22 (CHClF2) by replacing two Cl atoms with F.
\( \displaystyle \ce{CHCl3 + 2HF} \xrightarrow{\ce{SbCl5}} \ce{CHClF2 + 2HCl} \)
(D) Tetrachloromethane — This matches (I) propellants for aerosol cans. \( \ce{CCl4} \) is the raw material for chlorofluorocarbons (freons) used as refrigerants and aerosol propellants.