The statement "Ozone in the atmosphere is decreased by chlorofluorocarbons $(CF_2Cl_2)$" is:

For your agricultural field or garden,you have developed a compost-producing pit. Discuss the process in the light of bad odour,flies,and recycling of wastes for good produce.

Which one of the following statements is $NOT$ correct?

What is $DDT$ among the following?

The concentration of dissolved oxygen in water for the growth of fish should be more than $X \ ppm$ and the Biochemical Oxygen Demand $(BOD)$ in clean water should be less than $Y \ ppm$. $X$ and $Y$ in $ppm$ are,respectively:

$A$ large number of fish are suddenly found floating dead on a lake. There is no evidence of toxic dumping,but you find an abundance of phytoplankton. Suggest a reason for the fish kill.