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UPSC Prelims 2012 · Environment · Warming World
Consider the following statements: Chlorofluorocarbons, known as ozone-depleting substances, are used Which of the statements given above is/are correct?
- in the production of plastic foams
- in the production of tubeless tyres
- in cleaning certain electronic components
- as pressurizing agents in the aerosol cans
- (a) 1, 2 and 3 only
- (b) 4 only
- (c) 1, 3 and 4 only
- (d) 1, 2, 3 and 4
Show the answer and explanation
Answer: (c) 1, 3 and 4 only
Foams, electronics cleaning and aerosols.
Statement by statement
1. ✓ YES CFCs were blowing agents for plastic foams.
2. ✗ NO Tubeless tyres don’t use CFCs.
3. ✓ YES CFC-113 was used to clean electronic circuit boards.
4. ✓ YES CFCs were propellants in aerosol cans.
The idea
CFCs were called wonder chemicals: not poisonous, not flammable, very stable, and easy to turn from liquid to gas and back. These properties made them ideal wherever a safe, inert gas or liquid was needed. The same stability lets them survive long enough to reach the ozone layer.
Turns to gas easily → refrigerant in fridges and ACs → Inert gas under pressure → propellant in spray cans → Makes bubbles in plastic → foam blowing → Dissolves grease, leaves no residue → cleaning electronics
The trap
Tyres are the odd one out.
Also know
Other ozone-depleting substances: halons (fire extinguishers), carbon tetrachloride and methyl chloroform (solvents), methyl bromide (fumigant) and HCFCs (the first replacements, now being phased out). “Freon” was a trade name for CFCs. India completed its CFC phase-out by 2010.
🔒 CFC uses: refrigerants, aerosol propellants, foam blowing, solvents.