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

One mole of a monoatomic real gas satisfies the equation p(V $$-$$ b) = RT where b is a constant. The relationship of interatomic potential V(r) and interatomic distance r for the gas is given by

In the following reactions

Compound X is