Question

Read the following statements (A - D) related to the formation of ozone in the stratosphere and arrange them in the correct order.

A. Ozone gas is formed
B. 2 oxygen atoms are formed.
C. Oxygen atoms combine with molecular oxygen.
D. UV rays from the sun breakdown molecular oxygen.

• A. A → B → D → C
• B. D → B → C → A
• C. D → A → C → B
• D. B → C → A → D

Answer 1

The correct option is B D → B → C → A

Ozone is a molecule made up of three oxygen atoms, often referred to as O3.

The ozone layer is the high concentration of ozone that is found in the stratosphere around 15 – 30 km above the Earth's surface. It acts as a shield by absorbing ultraviolet radiation from the sun.

Stratospheric ozone is formed naturally by chemical reactions involving ultraviolet radiation and oxygen molecules.

The steps are as follows:

1. Ultraviolet radiations breakdown molecular oxygen (O2)
2. Two atoms of oxygen are formed.
3. Each of these highly reactive oxygen atoms combine with an oxygen molecule forming ozone
4. Thus, ozone (O3) is formed in the presence of ultraviolet radiation in the stratosphere.

Ozone formation occurs continuously whenever solar ultraviolet radiation is present in the stratosphere. The production of stratospheric ozone is balanced by its destruction in chemical reactions.

Hence option b is correct.