What is B.O.D.?</h2></div>

Which of the following conditions lead to formation of ozone?</h2></div>

How is the amount of biodegradable organic matter in sewage water estimated?

Drained sewage has B.O.D.</h2></div>

What is meant by depletion of ozone layers ? What are its causes?</h2></div>

ODS means</h2></div>

Which one of the following ways can be used to control global warming?

What is the main factor of sharply dropping the amount of ozone in the atmosphere?<br> </h2></div>