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.

Explanation

(i) Due to the formation of a layer of oxide i.e., `Al_2O_3` it becomes less reactive .
(ii) Na or Mg are more reactive metals as compared to carbon, so their oxides are more stable.
(iii) In solid NaCl, the movement of ions is not possible due to its rigid structure but in aqueous solution or molten state, the ions can move freely. These free ions are responsible for conduction of electricity.
(iv) Na,K,Ca and Mg and highly reactive metals and thus never found in their free state in nature.