From where are the biodegradable wastes generated?

The correct sequence of atmospheric layers starting from the Earth is:

The depletion of ozone in Antarctica is caused by the formation of which of the following substances?

What are pesticides and herbicides? Explain giving examples.

Which among the following is not a component of photochemical smog?

Given below are two statements.
Statement $I:$ In polluted water,values of both dissolved oxygen and $BOD$ are very low.
Statement $II:$ Eutrophication results in a decrease in the amount of dissolved oxygen.
In the light of the above statements,choose the most appropriate answer from the options given below.