Give reasons for the following:
(i) exists but does not.
(ii) Oxygen has less electron gain enthalpy with negative sign than sulphur.
(iii) is a stronger reducing agent than
(i) exists due to presence of empty d-orbitals and thus can expand its covalency upto 6 but cannot expand its covalency due to absence of d-orbitals.
(ii) The least negative electron gains enthalpy of oxygen is due to small size and more interelectronic repulsion with coming electron.
(iii) contains two P-H bonds while contains only one P-H bond therefore is a stronger reducing agent.