What do catalytic converters convert unburnt hydrocarbons into?

Given below are two statements:
Statement $I$: Electrostatic precipitator is most widely used in thermal power plants.
Statement $II$: Electrostatic precipitator in thermal power plants removes ionising radiations.
In the light of the above statements,choose the most appropriate answer from the options given below:

In almost all major Indian metropolitan cities like Delhi,the major atmospheric pollutants are .........

What does the given image represent?

In a pond,if there is too much wastage,then the $BOD$ of the pond will:

Arrange the following in ascending order based on their $BOD$ value:
$I -$ Sewage water,$II -$ Distilled water,$III -$ Tap water