1. Tardigrade
  2. Question
  3. Chemistry
  4. About 20 km above the earth, there is an ozone layer. Which one of the following statements about ozone and ozone layer is true?

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. About 20 km above the earth, there is an ozone layer. Which one of the following statements about ozone and ozone layer is true?

AIPMTAIPMT 1995The p-Block Elements - Part2

Solution:

Ozone is an allotropic form of oxygen. It is present in the upper atmosphere (about 20 km above the surface of the earth). It is believed to be formed in the upper atmosphere by the action of UV-rays on oxygen as $ \, \, \, \, \, \, 3O_2 \, + \, UV-rays \longrightarrow \, 2O_3,$ $ \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \Delta H = 142.7 kJ \, mol^{-1} $ Therefore, UV-rays, which are harmful to human beings are absorbed by oxygen to form ozone. The layer of ozone, thus formed also prevents the remaining UV-rays to reach the earth- surface.