5. Which of the following is associated with or true about Ozone (O3) ?
- Human exposure to ozone is not harmful.
- The chemicals used in fire extinguishers deplete ozone layer.
- The United Nations Environment Programme succeeded in freezing the production of ozone-depleting substances like CFCs only at the beginning of 21st century.
Select the correct answer using the codes given below:
- 2 and 3 only
- 2 only
- 1 and 3 only
- 1, 2 and 3
Chap-15, Pages 262, NCERT Class 10 Science
Ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen (O2) molecule. The higher energy UV radiations split apart some moleculer oxygen (O2) into free oxygen (O) atoms. These atoms then combine with the molecular oxygen to form ozone
The amount of ozone in the atmosphere began to drop sharply in the 1980s. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers. In 1987, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 levels.