Q121 (CAPF/2013) Environment & Ecology › Pollution & Conservation › Ozone layer protection Answer Verified

Statement I : Ozone is produced naturally by the action of ultraviolet radiation on oxygen molecule (02) in the upper atmosphere. Statement I : Ozone depletion has been caused by the release of chlorofluoro- carbons (CFCs) into the atmosphere.

Both the statements are individually true and Statement II is the correct explanation of Statement I

Both the statements are individually true but Statement II is not the correct explanation of Statement I

Statement I is true but Statement II is false

Statement I is false but Statement II is true

Result

Your answer: — · Correct: B

Explanation

Statement I is true as ozone is naturally produced in the stratosphere through the Chapman cycle. High-energy ultraviolet (UV) radiation photolyzes molecular oxygen (O2) into free oxygen atoms (O), which then combine with other O2 molecules to form ozone (O3) [5]. Statement II is also true; anthropogenic release of chlorofluorocarbons (CFCs) leads to ozone depletion. CFCs migrate to the stratosphere where UV radiation breaks them down, releasing chlorine radicals [3]. These radicals act as catalysts, where a single chlorine atom can destroy thousands of ozone molecules [2]. However, Statement II is not the explanation for Statement I. Statement I describes the natural formation process (production), while Statement II describes an anthropogenic destruction process (depletion). They are independent chemical phenomena occurring in the atmosphere, and the mechanism of depletion does not explain how ozone is naturally produced.

Sources

[5] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Ozonosphere > p. 276
[2] https://csl.noaa.gov/assessments/ozone/1985/vol1/chapter2.pdf
[3] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > The chemical reaction > p. 268
[1] Science , class X (NCERT 2025 ed.) > Chapter 13: Our Environment > 13.2.1 Ozone Layer and How it is Getting Depleted > p. 213

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Statement I : Ozone is produced naturally by the action of ultraviolet radiation on oxygen molecule (02) in the upper atmosphere. Statement I : Ozone depletion has been caused by the release of chlorofluoro- carbons (CFCs) into the atmosphere.

Explanation

SIMILAR QUESTIONS

Statement I : Skin cancer is generally caused by the ultraviolet radiation. Statement I : Stratosphere allows ultraviolet radiation to enter the earth from the sun.

Statement 1 : Ozone is a tn-atomic molecule of oxygen. Statement II ; Ozone is concentrated mainly in stratosphere.

Statement I : Oxygen gas is easily produced at a faster rate by heating a mixture of potassium chlorate and manganese dioxide than heating potassium chlorate alone. Statement I : Manganese dioxide acts as a negative catalyst.