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 :
Asked in UPSC CAPF 2011 · Topic: Ozone Layer (Mechanism of Ozone Depletion in the Stratosphere)
More Environment and Ecology questions
- CFCs (and other halogenated hydrocarbons like halons) are transported to the stratosphere where UV radiation breaks them down, releasing reactive chlorine and bromine atoms. These halogen atoms catalyze the destruction of ozone (O3). Thus, statement 1 is correct. 2. In polar regions during winter, extremely cold temperatures and the presence of the polar vortex (circumpolar winds) lead to the formation of Polar Stratospheric Clouds (PSCs), which can consist of ice crystals or nitric acid particles. These clouds provide surfaces for heterogeneous chemical reactions that convert less reactive halogen compounds into highly reactive forms (like Cl2). When sunlight returns in spring, these reactive forms are photolyzed, releasing large amounts of chlorine and bromine atoms, leading to rapid ozone depletion (the ozone hole). Thus, statement 2 is correct. 3. Ozone destruction primarily occurs through catalytic cycles involving reactive species. A key cycle involves chlorine monoxide (ClO) and oxygen atoms (O). Chlorine atoms react with ozone (Cl + O3 -> ClO + O2). Chlorine monoxide then reacts with an oxygen atom (ClO + O -> Cl + O2), regenerating the chlorine atom. The oxygen atoms (O) in the stratosphere are formed by the photolysis of oxygen molecules (O2) by UV light; these can be in ground (triplet) or excited (singlet) states, and both react with ClO. Thus, statement 3 refers to the reactive intermediates and partners involved in the catalytic destruction cycle and is correct. 57. Depletion of the stratospheric ozone layer occurs when molecules of ozone are destroyed by chemicals such as
- The supersonic jets cause pollution by the thinning of
- Statement (A) : Ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen molecule. Statement (B) : The decrease in ozone has been linked to synthetic chemicals like chloro-fluoro-carbons (CFCs). - Question not attempted
- Select the incorrect statement from the following - (1) In stratosphere chlorine atoms are released from Chlorofluorocarbons (CFCs) by UV rays. (2) Chlorofluorocarbons (CFCs) added to the stratosphere, have permanent and continuing effects on Ozone. (3) The ‘Kyoto protocol’ is for the substances that deplete Ozone layers. (4) In stratosphere, chlorine atoms act as a catalyst for degrading ozone.
- Which one is responsible for Ozone holes ?
- Which of the following is not an ozone depleting substance?
- Freons cause great environmental damage. They are :
- Which of the above statements are correct? A) B) C) D) Methane and Carbon Tetrachloride () are responsible for ozone depletion.