Explain the following (a) Reactivity of At decreases if it is dipped in `HNO_(3)`.
(b) Carbon cannot reduce the oxides of Na or Mg.
(c) mm is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.
(d) Iron articles are galvanised.
(e) Metals like Na, K. Ca and Mg are never found in their free state in nature.