What is the structural formula for Freon-12.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \(CCl_2F_2\)
Freons are the chlorofluorocarbons of methane and ethane. They are stable, unreactive, non-toxic and easily liquefied gases, used as refrigerants and aerosol propellants. Freon 12 is the most common of them: dichlorodifluoromethane, \( \ce{CCl2F2} \).
It is made from tetrachloromethane by Swarts reaction, in which two chlorine atoms are replaced by fluorine:
\( \displaystyle \ce{3CCl4 + 2SbF3} \xrightarrow{\ce{SbCl5}} \ce{3CCl2F2 + 2SbCl3} \)
Shortcut: Add 90 to the freon number: 12 + 90 = 102 gives the numbers of C, H and F atoms (1 C, 0 H, 2 F); the remaining valencies of carbon are filled by chlorine. So Freon 12 is \( \ce{CCl2F2} \).
NCERT (2026-27 edition):
Freons
