From where are the biodegradable wastes generated?

Biochemical oxygen demand $(BOD)$ value can be a measure of water pollution caused by organic matter. Which of the following statements is correct?

Which one of the following is mainly responsible for the depletion of the ozone layer?

Which of the following molecules is present in photochemical smog?

Identify the true $(T)$ and false $(F)$ statements regarding the disease known as fluorosis:
$(1)$ Fluorosis weakens teeth and bones.
$(2)$ Fluorosis is caused by fluoride concentrations greater than $2 \ ppm$ $(2 \ mg/L)$.
$(3)$ Fluorosis causes neuromuscular disorders.
$(4)$ Fluoride deficiency causes fluorosis.

What is acid rain? Explain the formation of acid rain by atmospheric pollutants.