Which of the following is a secondary pollutant?

In which state/country are Ecosan toilets not found?

Choose the correct option regarding the following statements:
$(1)$ $CO_2$ contribution in global warming is $60\%$.
$(2)$ Greenhouse effect occurs due to deforestation.
$(3)$ Due to the greenhouse effect,the present average temperature at the surface of the Earth is $15^oC$.
$(4)$ The amount of $DDT$ in small fish is $0.05\ ppm$.

Which of the following is a pollution-related disease?

Arrange $CFC, CH_4, N_2O$ and $CO_2$ in decreasing order according to their contribution in the greenhouse effect.

What is the ascending order of $BOD$ for the following: Sewage $(S)$,Paper mill effluent $(PE)$,Distillery effluent $(DE)$,and Sugar factory effluent $(SE)$?