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RAS question

Which greenhouse gas has the highest Global Warming Potential (GWP)?

Correct answer: (A) Sulphur hexafluoride.

Sulphur hexafluoride (SF6) has a 100-year Global Warming Potential of 23,500 relative to carbon dioxide, higher than nitrous oxide, carbon dioxide and methane.

  1. (A)

    Sulphur hexafluoride

  2. (B)

    Nitrous oxide

  3. (C)

    Carbon dioxide

  4. (D)

    Methane

Explanation

Global Warming Potential compares the warming effect of a gas over a fixed period against carbon dioxide, whose GWP is the baseline of 1. EPA lists SF6 with a 100-year GWP of 23,500, far above the values for methane, nitrous oxide and carbon dioxide. EPA also notes that SF6 is used as an insulating gas in electrical transmission equipment, including circuit breakers. Sulphur hexafluoride therefore has a much stronger warming impact than the better-known greenhouse gases.

Why the other options are wrong

  • (B) Nitrous oxide is wrong because its GWP is about 265-298, far below SF6's 23,500.
  • (C) Carbon dioxide is wrong because it is the reference gas with a GWP of 1, so it cannot be the highest-GWP gas.
  • (D) Methane is wrong because its 100-year GWP is about 28-36, much lower than SF6's 23,500.

Concept

Greenhouse-gas potency in Environment and Ecology depends on GWP as a comparison with carbon dioxide. The concept recurs in RAS because climate-change questions often ask aspirants to rank gases by warming impact rather than by familiarity.

Source

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