Which of the following are greenhouse gases?

1.Carbon dioxide

2.Nitrogen dioxide

3.Methane

4.Chlorofluorocarbons

5.Benzene

A1, 2 & 3 only

B1, 2, 3 & 4 only

C1, 3 & 4 only ✓ Correct

D3, 4 & 5 only

Correct answer: (C) 1, 3 & 4 only

Explanation

Carbon dioxide, methane and chlorofluorocarbons are all greenhouse gases.

Statement 1 holds, as carbon dioxide is the leading greenhouse gas.

Statement 3 holds, since methane traps far more heat per molecule.

Statement 4 holds, because chlorofluorocarbons are potent, long-lived greenhouse gases.

Statement 2 fails, as nitrogen dioxide is an air pollutant rather than a counted greenhouse gas.

Statement 5 fails, since benzene is a toxic hydrocarbon, not a greenhouse gas.

Nitrous oxide, distinct from nitrogen dioxide, is the nitrogen-based greenhouse gas.

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