Which of the following is true about freons?

Step 1: Evaluate each statement

(a) "These are chlorofluorocarbon compounds"

Analysis:

Freons are CFCs (chlorofluorocarbons):

• Contain carbon, chlorine, and fluorine
• Examples: $\ce{CFCl3}$, $\ce{CF2Cl2}$
• Used as refrigerants, propellants

TRUE ✓

(b) "These are chemicals causing skin cancer"

Analysis:

Freons indirectly contribute to skin cancer:

• Deplete ozone layer
• More UV radiation reaches Earth
• UV causes skin cancer

But freons themselves don't directly cause skin cancer.

Misleading/FALSE ✗

(c) "These are radicals of chlorine and chlorine monoxide"

Analysis:

Freons are stable molecules, not radicals.

In the stratosphere, freons break down to form radicals: $\ce{CFCl3 ->[UV] CFCl2• + Cl•}$

But freons themselves are not radicals.

FALSE ✗

(d) "All radicals are called freons"

Analysis:

Completely false. Radicals are reactive species with unpaired electrons. Freons are specific CFC compounds.

FALSE ✗

Answer: (a) These are chlorofluorocarbon compounds

Key Points:

Freons (CFCs):

• Chlorofluorocarbon compounds
• Stable, non-toxic, non-flammable
• Used in refrigeration, air conditioning
• Cause ozone depletion

Ozone depletion mechanism:

1. CFC release: $\ce{CFCl3}$ rises to stratosphere
2. UV photolysis: $\ce{CFCl3 ->[UV] CFCl2• + Cl•}$
3. Ozone destruction: $\ce{Cl• + O3 -> ClO• + O2}$
4. Regeneration: $\ce{ClO• + O -> Cl• + O2}$
5. Net: $\ce{O3 + O -> 2O2}$ (one Cl• destroys many $\ce{O3}$ molecules)

Health effects:

• Ozone depletion → more UV-B radiation
• UV-B → skin cancer, cataracts
• Freons don't directly cause cancer