Question

One of allotrope of oxygen is ozone. It is a pale-blue poisonous gas with strong odour.
A. True
B. False

Answer 1

There are many known allotropes of oxygen. One of the allotrope of oxygen is allotrope. Ozone is a highly toxic gas and acts as a sunblock for our earth. Chemical formula for ozone is ${O_3}$ . Ozone acts as a layer in the Stratosphere where Ozone concentration is high. Ozone is found in the stratosphere which is $10 - 50Km$ above the ground.

Complete step by step answer:
The upper Stratosphere consists of high concentration of ozone $\left( {{O_3}} \right)$, which protects our life and covers the whole planet from the harmful ultraviolet (UV) radiation coming from the sun towards the earth. Ozone $\left( {{O_3}} \right)$ is present in upper stratosphere and obtained as a byproduct of ultraviolet (UV) radiation acting on oxygen molecules $\left( {{O_2}} \right)$ .
Now first we will discuss the formation of ozone $\left( {{O_3}} \right)$. First step is that the UV radiation breaks molecular oxygen $\left( {{O_2}} \right)$ into free oxygen $\left( O \right)$ atoms. The first step can be written as follows:
${O_2}(g)\xrightarrow{{UV}}O(g) + O(g)$
The next step is that oxygen $\left( O \right)$ atoms will combine with oxygen molecules $\left( {{O_2}} \right)$ to form ozone oxygen molecules $\left( {{O_3}} \right)$.
$O(g) + {O_2}(g)\overset {UV} \leftrightarrows {O_3}(g)$

When an ozone $\left( {{O_3}} \right)$ molecule absorbs UV radiation it breaks in a molecular oxygen $\left( {{O_2}} \right)$ and free oxygen $\left( O \right)$ atoms. The free oxygen $\left( O \right)$ atom obtained again combines with molecular oxygen $\left( {{O_2}} \right)$ to form ozone$\left( {{O_3}} \right)$. This cycle is called an ‘Oxygen-Ozone’ cycle and due to this cycle harmful ultraviolet (UV) radiations are continuously absorbed as heat.
Final Result: One of allotrope of oxygen is ozone. It is a pale-blue poisonous gas with strong odour.

So, the statement is true.

Note: The Ozone $\left( {{O_3}} \right)$ molecule absorbs ultraviolet (UV) rays between $310$ to $210$ nm wavelength. chlorofluorocarbon compounds (CFCs), nitrogen oxides, chlorine, tetrachloride are ozone depleting substances (ODS). More than $1000ppm$ of ozone leads to dizziness and headache.