Radioactive fall out contaminates</h2></div>

BOD of eutrophied lake will be</h2></div>

BOD (biological oxygen demand) is</h2></div>

Define BOD. What is its significance in an aquatic ecosystem?</h2></div>

Global warming is caused by greenhouse effect. Justify.<br> </h2></div>

Ozone layer of upper atmosphere is being destroyed by</h2></div>

Which of the following is depleted by CFCs?</h2></div>

Ozone layer of upper atmosphere is being destroyed by </h2></div>