Which of the following has an $S-S$ bond?

How many total statements are correct in the following?
$(i)$ $SO_2$ - antichlor,preservative
$(ii)$ $O_3$ - Disinfectant
$(iii)$ $Cl_2$ - Antiseptic
$(iv)$ $O_2$ - used in oxy-acetylene welding
$(v)$ $PH_3$ - used in smoke screens
$(vi)$ $HNO_3$ - Pickling of stainless steel

Which among the following is a group $16$ element?

Given below are two statements:
Statement-$I$: $\alpha$ and $\beta$ forms of sulphur can change reversibly between themselves with slow heating or slow cooling.
Statement-$II$: At room temperature the stable crystalline form of sulphur is monoclinic sulphur.
In the light of the above statements,choose the correct answer from the options given below:

When $SO_2$ is passed through acidified $K_2Cr_2O_7$ solution:

Which of the following compounds has the maximum number of oxo groups (terminal $O$ atoms bonded to the central atom by a double bond)?