Question

5. Is there water in the stratosphere? How is the stratospheric water formed (write the formula)? How is the stratospheric water harmful by writing certain reactions? 6. How many sub categories is UV divided and How each region transports through the atmosphere? Which species does absorb UV? 7. Write the major chemical equations on 03 formation and destruction? How does chlorofluorocarbon affect the 03 by writing certain chemical equations?

Answer 1

5. There is very little water in the form of water vapour in stratosphere. Stratospheric water is further formed from the reaction of methane with ozone. As we can see oxygen atom reacts with water to give OH^​​​•  which further reacts with methane to give water and ^•CH₃ free radical. Presence of water starts a chain reaction leading to the destruction of ozone layer.

O-D 0'9 HO. HO CHA +'OH Cmethane Cwlaten The methyl taee sadical aailable to tunthes eaction and causes destouction o OZOne.

6. Ultraviolet radiation or UV rays are mainly of 3 types. These are UVA, UVB and UVC. The longer wavelength UVA and some amount of UVB is transmitted through the atmosphere and reaches earth's surface while all of UVC is absorbed.

UVC is absorbed by the ozone layer in the stratosphere. Ozone (O_​​​3 ) absorbs it.

7. Formation and Destruction of ozone is called the Chapman cycle. The reactions are described below.

CHAPMAN CYCLE CHeation aOzOne (Photolypie) 20 (a<24Om) O+ o M Og+M (Ozone) Destauction o4 ozone UV-C O'3 O O + K.E

Chlorofluorocarbons (CFCs) cause destruction of the ozone layer in the following ways.

CFCIS CFCI2+Cl Clo+ 02 The cl atem poduced is free to attack othen ozone pedes. Thus CFCS cause destouction of 0zone.