The first commercial pesticide was:

Drinking mineral water with a very low level of pesticides (about $0.02 \ ppm$) for long periods may:

List any two adverse effects of particulate matter on human health.

Which one of the following is not correct with regard to the harmful effects of particulate matter of the size $2.5 \ \mu m$ or less?

What does '$X$' represent in the given figure?

Discuss the following in brief:
$(a)$ Greenhouse gases
$(b)$ Catalytic converters
$(c)$ Ultraviolet-$B$ $(UV-B)$