Which of the following statements is/are correct concerning Ozone gas? 1. Good ozone is found in the upper part of the atmosphere called the Troposphere. 2. The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU).  3. Research indicates that depletion of the stratospheric ozone layer is being reduced worldwide.  Select the correct answer using the code given below.

Which of the following statements is/are correct concerning Ozone gas? 1. Good ozone is found in the upper part of the atmosphere called the Troposphere. 2. The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU).  3. Research indicates that depletion of the stratospheric ozone layer is being reduced worldwide.  Select the correct answer using the code given below. Correct Answer 2 and 3

The correct answer is 2 and 3.

Key Points

• Good ozone is found in the upper part of the atmosphere called the stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun. Hence, Statement 1 is incorrect.
• UV rays are highly injurious to living organisms since the DNA and proteins of living organisms preferentially absorb UV rays, and their high energy breaks the chemical bonds within these molecules.
• The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU). Hence, Statement 2 is correct.
• Ozone gas is continuously formed by the action of UV rays on molecular oxygen and is also degraded into molecular oxygen in the stratosphere.
• There should be a balance between the production and degradation of ozone in the stratosphere. Of late, the balance has been disrupted due to the enhancement of ozone degradation by chlorofluorocarbons (CFCs).
• CFCs find wide use as refrigerants. CFCs discharged in the lower part of the atmosphere move upward and reach the stratosphere.
• In the stratosphere, UV rays act on them releasing Cl atoms.
  • Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts;
  • Cl atoms are not consumed in the reaction.
• Research indicates that the depletion of the stratospheric ozone layer is being reduced worldwide. Thinning of the protective ozone layer can be observed using satellite measurements, particularly over the Polar Regions. Hence, statement 3 is correct.