Which of the following processes would explain ozone losses in the atmosphere ? When ozone is exposed to 1. CFCs and UV radiation. 2. long winter circumpolar winds to form ice crystals. 3. singlet oxygen atom and chlorine monoxide. Select the correct answer using the code given below ;

Ozone depletion occurs through several interconnected processes. First, CFCs transported to the stratosphere are photolyzed by UV radiation, releasing free chlorine atoms [c1, c4, t4]. These chlorine atoms initiate a catalytic cycle where they react with ozone to form chlorine monoxide (ClO) [c1, t2]. Second, during the long winter, circumpolar winds create a stable polar vortex, leading to extremely low temperatures that allow the formation of Polar Stratospheric Clouds (PSCs) consisting of ice crystals [c2, t5, t7]. These crystals provide the necessary surface for chemical reactions that convert inactive chlorine reservoirs into active forms [c2, t7]. Third, the catalytic destruction cycle is completed when chlorine monoxide (ClO) reacts with a singlet oxygen atom (O), reforming the chlorine catalyst and producing molecular oxygen [c1, t2]. This continuous cycle allows a single chlorine atom to destroy thousands of ozone molecules [c1, c3].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > The chemical reaction > p. 268
2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > R9.R.4. Role of polar stratospheric clouds in ozone depletion. > p. 270
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Ozonosphere > p. 276
4. [4] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > ozone depletion > p. 13
5. [5] https://csl.noaa.gov/assessments/ozone/2006/twentyquestionsposter.pdf