In the experiment above, X could be a solution of
A.
sodium trioxonitrate (V) and ammonium chloride
B.
sodium trioxonitrate (lll) and ammonium chloride
C.
lead (ll) trioxonitrate (V) and copper turnings
D.
potassium trioxonitrate (V) and copper turnings
Correct answer is B
Nitrogen is prepared in the laboratory by heating an equimolar aqueous solution of ammonium chloride and sodium nitrite. The ammonium nitrite formed as a result of a double decomposition reaction, decomposes to form nitrogen gas.
\(NH_4Cl_{(aq)}+NaNO_{2(aq)} → NH_4NO_{2(aq)}+NaCl_{(aq)}\)
\(NH_4NO_{2(aq)} →N_{2(g)} +2H_2O_{(l)}\).
(source: understanding chemistry by G O Ojukuku)