The deposition of $X$ and $Y$ on ground surfaces is referred to as wet and dry depositions,respectively. $X$ and $Y$ are:

On the surface of polar stratospheric clouds,hydrolysis of chlorine nitrate $(ClONO_2)$ gives $A$ and $B$,while its reaction with $HCl$ produces $B$ and $C$. $A, B$ and $C$ are,respectively:

Ozone is a gas heavier than air. Why does it not settle around the Earth's surface?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R:$
Assertion $A:$ Polluted water may have a value of $BOD$ of the order of $17 \, ppm$.
Reason $R:$ $BOD$ is a measure of oxygen required to oxidise both the biodegradable and non-biodegradable organic material in water.
In the light of the above statements,choose the most appropriate answer from the options given below.

The $BOD$ values for pure water and highly polluted water are respectively

How is electricity produced in a thermal power station?