Which of the following is the structure of oleum?

In the manufacture of sulphuric acid by the contact process,the Tyndall box is used to

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.

In the preparation of sulphuric acid,$V_2O_5$ is used in the reaction which is:

Provide information about simple oxides.

What happens when:
$(i)$ Concentrated $H_2SO_4$ is added to calcium fluoride
$(ii)$ $SO_3$ is passed through water?