Consider the following sulphur-based oxoacids: $H_2SO_3$,$H_2SO_4$,$H_2S_2O_8$,and $H_2S_2O_7$. Among these oxoacids,the number of those with a peroxo $(O-O)$ bond is $..........$

Identify the correct statements from the following:
$i$. Sulphuric acid is manufactured by contact process.
$ii$. $SO_3$ dissolves in $H_2SO_4$ to form pyrosulphuric acid $(H_2S_2O_7)$.
$iii$. $H_2SO_4$ is used in the manufacture of fertilisers such as ammonium sulphate and super phosphate.
$iv$. In the reaction,$S + 2H_2SO_4 (\text{conc.}) \longrightarrow 3SO_2 + 2H_2O$,$H_2SO_4$ is oxidised to $SO_2$.

Which one is known as oil of vitriol?

Peroxymonosulfuric acid is known as ..........

Which form of sulphur shows paramagnetic behaviour?

Name the gas that can readily decolourise acidified $KMnO_4$ solution.