BOD of lake becomes high by :-</h2></div>

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

The natural vegetation in a particular area is termed as <br> </h2></div>

Free radicals of bromine are more destructive than _______ in case of ozone depletion.<span><br> </span&g…

What is the toxic substance contained by typical electronic waste?</h2></div>

<span>What is the importance of oxygen in water for living organisms?</span></h2></div>

Which of the following is an effect of the high dose of UV-B?

Which one of following pairs of gases is the major cause of greenhouse effect?</h2></div>