Explanation
- A
Only one
Only one. HFCs appear in more than one of the listed uses.
- B
Only two
Only two. Aerosols, foam blowing and fire suppression all use HFCs.
- C
Only three
Only three. Aerosols, foam agents and fire retardants / suppression. Lubricants are not an HFC use-class here.
- D
All four
All four. Lubricants are oils, not HFC applications in this listing.
Summary. Official key is (c) only three. Hydrofluorocarbons replaced CFCs in aerosols, foam blowing and some fire-extinguishing systems. They are refrigerants too. They are not used as lubricants, so four is too many.
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
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2017 · Q65 · General Studies · 2 marks
Consider the following statements: 1. Climate and Clean Air Coalition (CCAC) to Reduce Short Lived Climate Pollutants is a unique initiative of G20 group of countries. 2. The CCAC focuses on methane, black carbon and hydrofluorocarbons. Which of the statements given above is/are correct?