Indiscriminate use of $DDT$ is undesirable because

Which gas is formed due to lightning in the atmosphere?

The consequence of global warming may be the following:

$A$ farmer is using pesticides in his field. He uses the produce from his field as food for fish. He is told that the fish are not fit for human consumption because large amounts of pesticides were found in the fish cells. How is this possible? Explain.

Match List-$I$ and List-$II$:

List-$I$	List-$II$
$(a)$ Carbon monoxide	$(i)$ Carcinogenic
$(b)$ Sulphur dioxide	$(ii)$ Metabolized by pyrus plants
$(c)$ Polychlorinated biphenyls	$(iii)$ Haemoglobin
$(d)$ Oxides of nitrogen	$(iv)$ Stiffness of flower buds

Choose the correct answer from the options given below:

Which of the following,when present in excess in drinking water,causes the disease methemoglobinemia?