When $PbO_2$ reacts with concentrated $HNO_3$,the gas evolved is

Explain why ozone $(O_3)$ is thermodynamically less stable than oxygen $(O_2)$?

Which compound of sulfur is used as a refrigerant?

Which of the following is a colourless gas that exhibits both oxidising and reducing properties?

Below are two statements. One is labeled as Assertion $(A)$ and the other as Reason $(R):$
Assertion $(A):$ $H_2Te$ is more acidic than $H_2S$.
Reason $(R):$ The bond dissociation enthalpy of $H_2Te$ is less than that of $H_2S$.
In the context of the above statements,choose the correct answer from the following options:

Explain variations in atomic radii and ionisation enthalpies in group-$16$.