Which of the following are responsible for the formation and destruction of ozone (O3) in the upper atmosphere?

1.Solar radiation

2.Oxides of nitrogen (NOx)

3.Black carbon

4.Chlorine (Cl)

5.Ammonia (NH3)

A1, 2 & 4 only ✓ Correct

B2, 3 & 4 only

C3, 4 & 5 only

D1, 3 & 5 only

Correct answer: (A) 1, 2 & 4 only

Explanation

Solar radiation, oxides of nitrogen and chlorine are all involved in making and breaking ozone in the upper atmosphere.

Statement 1 is right because solar ultraviolet light splits oxygen and forms ozone.

Statement 2 is right as nitrogen oxides catalytically destroy ozone.

Statement 3, black carbon, plays no part in this ozone chemistry, and Statement 5, ammonia, is likewise not involved.

Statement 4 is right because chlorine atoms catalytically break down ozone, giving solar radiation, nitrogen oxides and chlorine.

A single chlorine atom from CFC breakdown can destroy thousands of ozone molecules.

Want more like this? Create a free account to practise a full test, track your progress, and get spaced-repetition review.