What is the color of ozone $(O_3)$?

In the preparation of sulphuric acid from sulphur dioxide in the lead chamber process,what substance is used as a catalyst?

Match List-$I$ with List-$II$ :

List-$I$ (Oxoacids of Sulphur)	List-$II$ (Bonds)
$A$. Peroxodisulphuric acid	$I$. Two $S-OH$,Four $S=O$,One $S-O-S$
$B$. Sulphuric acid	$II$. Two $S-OH$,One $S=O$
$C$. Pyrosulphuric acid	$III$. Two $S-OH$,Four $S=O$,One $S-O-O-S$
$D$. Sulphurous acid	$IV$. Two $S-OH$,Two $S=O$

Choose the correct answer from the options given below.

What is true about $H_2S_nO_6$ (Polythionic acid)?

How is $O_3$ estimated quantitatively?

Given below are two statements:
Statement $I$: Oxygen being the first member of group $16$ exhibits only $-2$ oxidation state.
Statement $II$: Down the group $16$ stability of $+4$ oxidation state decreases and $+6$ oxidation state increases.
In the light of the above statements,choose the most appropriate answer from the options given below: