Question

How does the ozone molecule form?
a. Ozone $(O_3)$ is a molecule formed by two atoms of oxygen.
b. Ozone $(O_3)$ is a molecule formed by three atoms of oxygen.
c. Ozone $(O_3)$ is a molecule formed by four atoms of oxygen.
d. None of these.

Answer 1

Hint: Ozone is an inorganic molecule having a chemical formula $O_3$ . It has a pungent smell and is blue color gas. It is the allotrope of oxygen. It is formed by the action of ultraviolet light and electrical discharges that occurs within the earth’s atmosphere.

Complete answer:
- Ozone is an inorganic molecule and an allotrope of oxygen having three atoms in the molecule instead of the usual two. It is a blue gas produced by the electrical discharge of oxygen.
- In the stratosphere, it forms an ozone layer. The ozone layer acts as an ozone shield protecting the earth's biota from the harmful effects of strong UV radiation.

Ozone is produced in two steps:
- In the first step, the UV rays break up an oxygen molecule into two oxygen atoms
- In the second step, each atom undergoes a binding collision with the other oxygen molecule and thus forming an ozone molecule.
- To sum up the overall process, the three oxygen molecules and the UV rays from sunlight form two ozone molecules.

- A balance is established between the generation and destruction of $O_3$ , leading to a steady-state concentration of the ozone layer in the stratosphere.

Hence, the correct answer is option (B).

Note: The highest amount of ozone in the atmosphere is in the stratosphere between 20 and 26 km above the sea level. The thinning of the ozone layer results in an increase in the UV-B radiation reaching the earth's surface which causes skin cancer, cataract, destroys the immune system, etc.