Currently,the Government of India has approved the blending of alcohol in petrol. What percentage of alcohol blending in petrol has been approved?

The secondary pollutant that inhibits the Hill reaction is:

In which one of the following have the $BOD$ (Biochemical Oxygen Demand) of sewage $(S)$,distillery effluent $(DE)$,paper mill effluent $(PE)$,and sugar mill effluent $(SE)$ been arranged in ascending order?

What are the full forms of the following abbreviations?
$(i)$ $CNG$
$(ii)$ $DDT$

Given below are two statements:
Statement $I:$ In a scrubber,the exhaust from the thermal plant is passed through a spray of water or lime to remove gases like $SO_2$.
Statement $II:$ Particulate matter $(PM\,2.5)$ cannot be removed by a scrubber but can be removed by an electrostatic precipitator.
In the light of the above statements,choose the most appropriate answer from the options given below:

Acid rain:
$(a)$ Causes necrosis
$(b)$ Converts chlorophyll-$a$ into phaeophytin
$(c)$ Responsible for formation of $PAN$