What is the amount of oxygen consumed by bacteria to oxidize all the organic matter present in one liter of water called?

Electrostatic Precipitator $(ESP)$:
$I.$ Is an electrical device to remove particulate matter present in the exhaust of thermal power plant.
$II.$ More than $99\, \%$ particulate matter can be removed by this method.
$III.$ $ESP$ has electrode wires and a stage of collecting plates.
Which of the statements given above are correct?

What is $BOD$?

What is the full form of $CNG$?

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:

An electrostatic precipitator is used in thermal power plants to remove $...........$ from the exhaust gases.