'A' involves heating when the volatile matter escapes leaving behind the metal oxide. Here 'A' means,
Name :
(a) a nitrate of metal which on heating does not give nitrogen dioxide.
(b) a nitrate which on heating leaves no residue behind.
(c) a metal nitrate which on heating is changed into metal oxide.
(d) a metal nitrate which on heating is changed into metal.
(e) a solution which absorbs nitric oxide.
(f) the oxide of nitrogen which turns brown on exposure to air. How is it prepared ?