Acid rain is caused by the presence of $X$ and $Y$ in air. $X, Y$ are respectively

During a school field trip,a botany student visited a beautiful pond in a village and collected some plants. He observed that villagers were washing clothes there,and household waste was spoiling its beauty in some areas. After a few years,he revisited the pond and found it completely covered with algae,emitting a foul smell,and the water had become unusable. Can you describe this condition of the pond?

Which of the following solvents reduces the environmental pollution?

Excessive release of $CO_2$ into the atmosphere results in

Cataract and skin cancer are caused by

$BOD$ values (in $ppm$) for clean water $(A)$ and polluted water $(B)$ are expected respectively: