Chlorofluorocarbons (CFCs), important greenhouse gases,

1.Are toxic.

2.Vaporise just below room temperature.

3.Are flammable.

4.Are very stable.

5.Destroy ozone.

A1, 2 & 3 only

B2, 3 & 4 only

C2, 4 & 5 only ✓ Correct

D3, 4 & 5 only

Correct answer: (C) 2, 4 & 5 only

Explanation

CFCs vaporise near room temperature, are chemically very stable and destroy ozone.

Statement 1 is wrong, as CFCs are essentially non-toxic to humans.

Statement 2 is correct, since CFCs boil just below room temperature.

Statement 3 is wrong, as CFCs are non-flammable, which made them popular refrigerants.

Statement 4 is correct, as their high stability lets them reach the stratosphere intact.

Statement 5 is correct, as ultraviolet light frees their chlorine to destroy ozone.

This stability and ozone damage led to their phase-out worldwide.

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