Concentrated $H_2SO_4$ reacts with $PCl_5$ to produce

Explain the contact process for the manufacture of sulphuric acid.

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

Which of the following activities results in the formation of oleum in the manufacture of sulphuric acid by the contact process?

The number of $S=O$ bonds present in sulphurous acid,peroxodisulphuric acid and pyrosulphuric acid,respectively are :

$A$ sulphate of a metal $(A)$ on heating evolves two gases $(B)$ and $(C)$ and an oxide $(D).$ Gas $(B)$ turns $K_2Cr_2O_7$ paper green while gas $(C)$ forms a trimer in which there is no $S-S$ bond. Compound $(D)$ with $HCl$ reacts to form a compound $(E)$ which exists as a dimer. Compounds $(A)$,$(B)$,$(C)$,$(D)$ and $(E)$ are respectively: