Question

Consider the following statements regarding ozone:

1. It is continuously being produced and destroyed

2. It helps to sustain life on earth

3. It is formed in the atmosphere through photochemical reaction

Which of the above statements are correct?

1. 1 and 2 only
2. 1 and 3 only 
3. 2 and 3 only
4. 1, 2 and 3

Answer 1

Correct Answer - Option 4 : 1, 2 and 3

Ozone:

• Ozone is formed throughout the atmosphere in multistep chemical processes that require sunlight. In the stratosphere, the process begins with an oxygen molecule (O₂) being broken apart by ultraviolet radiation from the Sun.
• In the lower atmosphere (troposphere), ozone is formed by a different set of chemical reactions that involve naturally occurring gases and those from pollution sources.
• Ozone abundances in the stratosphere and troposphere are determined by the balance between chemical processes that produce and destroy ozone.
• The balance is determined by the amounts of reactive gases and how the rate or effectiveness of the various reactions varies with sunlight intensity, location in the atmosphere, temperature, and other factors.
• As atmospheric conditions change to favour ozone-producing reactions in a certain location, ozone abundances increase.
• Similarly, if conditions change to favour other reactions that destroy ozone, abundances decrease.
• Global ozone has decreased during the past several decades because the amounts of reactive gases containing chlorine and bromine have increased in the stratosphere due to human activities

 

Importance of ozone:

• The ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (UVR) from the sun, protecting life on Earth from its potentially harmful effects.
• When the sky is clear, there is an inverse relationship between stratospheric ozone and solar UVR measured at the Earth’s surface. That is, the lower the ozone levels, the higher the solar UVR.