In the following reactions, the major product W is

The correct statements regarding (i) HClO, (ii) HClO₂, (iii) HClO₃ and (iv) HClO₄ is (are)

The pairs of ions where BOTH the ions are precipitated upon passing H₂S gas in presence of dilute HCl, is(are)

Under hydrolytic conditions, the compounds used for preparation of linear polymer and for chain termination, respectively, are