.
(b) Carbon cannot reduce the oxides of Na or Mg.
(c) NaCI 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.
Answer:
(a)
is an oxidising agent.
When aluminium is dipped in , an oxide layer
(of aluminium) is formed on the surface of the metal, which prevents it from
further reaction. (1)
(b) Na, Mg, etc metals are quite reactive and present towards
the top of the reactivity series. Hence, their affinity with oxygen is high and
their oxides cannot be reduced by carbon. (1)
(c) Ions of NaCI cannot move to carry the charge in dry
state. But they are free in molten state and in aqueous solution to carry the
charge and hence, NaCI conducts electricity in molten state. (1)
(d) In galvanisation a thin layer of zinc is formed over the
iron articles by dipping them in molten zinc, which prevents iron from
corrosion. (1)
(e) These metal are quite reactive so they cannot exist in
free state and hence, they are found in nature in the form of their
compounds. (1)
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