$V_2O_5$ is useful as a catalyst in:

What are the values of electron gain enthalpy in groups $16$ and $17$? How do they change?

Which of the following is formed when $SO_3$ is absorbed by concentrated $H_2SO_4$?

Identify the correct order of acidity of hydrides of $16^{th}$ group elements from the following.

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$ : Both rhombic and monoclinic sulphur exist as $S_8$ while oxygen exists as $O_2$.
Reason $(R)$ : Oxygen forms $p \pi-p \pi$ multiple bonds with itself and other elements having small size and high electronegativity like $C, N$,which is not possible for sulphur.
In the light of the above statements,choose the most appropriate answer from the options given below:

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