Domestic sewage contains nutrients like nitrogen and phosphorus which favours the excessive growth of planktonic (free-floating) algae which can accelerate which of the following phenomenon?

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

Estuaries occur in which of the following Indian states?

Photochemical smog formed in congested metropolitan cities mainly consists of

Consider the following statements about Ramesh Chandra Dagar's work in the field of organic farming:
$I.$ Ramesh Chandra Dagar's work includes bee-keeping,dairy management,water harvesting,composting,and agriculture in a chain of processes.
$II.$ In this process,there is no need to use chemical fertilisers for crops as cattle excreta is used as manure.
$III.$ Crop waste is used for making compost,which is used as natural fertilizer.
$IV.$ Compost generates natural gas,which is used for the energy needs of the farm.
Which of the statements given above are correct?

Among the $X$ most polluted cities in the world,Delhi ranked at $Y$ position. Identify $X$ and $Y$.