Which of the following formulas represents fuming sulfuric acid (oleum)?

Which among the following is $NOT$ the use of $SO_2$ gas?

Concentrated $H_2SO_4$ reacts with $PCl_5$ to produce

Given below are two statements: Statement $I$: The covalency of oxygen is generally two but it can exceed up to four. The oxidation state of oxygen in $SO_2$ is $-2$ and in $OF_2$ it is $+2$. Statement $II$: The anomalous behaviour of oxygen when compared to the other elements of group $16$ is due to its small size and high electronegativity. In the light of the above statements, choose the correct answer from the options given below.

Identify the correct order of thermal stability of hydrides of $16$ group elements from the following.

Identify the incorrect statement regarding ozone $(O_3)$.