To which class of pesticides do $DDT$,$BHC$,aldrin,and endosulphan belong?

Which of the following is a biodegradable pollutant?

Which measures can be taken to control noise pollution?
$I-$ Use of sound-absorbent materials or mufflers in industries.
$II-$ Creating horn-free zones around hospitals and schools.
$III-$ Setting permissible sound levels for firecrackers and loud speakers.
$IV-$ Restricting the use of loudspeakers after a certain time.

Choose the incorrect sentence regarding $BOD$.

What is the result of the presence of excessive nutrients in water bodies?

Which among the following is likely to have the highest levels of $D.D.T.$ depositions in its body?