Consider the following : 1. Aerosols 2. Foam agents 3. Fire retardants 4. Lubricants In the making of how many of the above are hydrofluorocarbons used?
- (a) Only one
- (b) Only two
- (c) Only three ✓ UPSC's answer
- (d) All four
Why the answer is (c)
• Hydrofluorocarbons (HFCs) replaced ozone-depleting CFCs and HCFCs but are potent greenhouse gases, now being phased down under the Kigali Amendment to the Montreal Protocol.
• They are used as propellants in aerosols (item 1), as blowing agents in foam manufacture (item 2) and as fire-suppression/retardant agents in place of halons (item 3).
• Their main use is as refrigerants in air-conditioning and refrigeration.
• HFCs are not used in making lubricants, which are hydrocarbon oils, esters or silicones (item 4 does not qualify).
• Hence three of the four, option (c).
Why the other options are wrong
- (a) Only one
- HFCs are used in aerosols, foams and fire retardants, so the count is three.
- (b) Only two
- Three applications, not two, use HFCs.
- (d) All four
- Lubricants do not use HFCs.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2023, held on 28 May 2023. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.