Consider the following equilibrium $$AgCl \downarrow + 2N{H_3} \rightleftharpoons {\left[ {Ag{{\left( {N{H_3}} \right)}_2}} \right]^ + } + C{l^ - }$$        White precipitate of $$AgCl$$  appears on adding which of the following ?

Solution :
$$2HN{O_3}\left( {aq} \right) + {\left[ {Ag{{\left( {N{H_3}} \right)}_2}} \right]^ + } + C{l^ - } \to AgCl\left( s \right) \downarrow + 2N{H_4} + 2NO_3^ - $$
When nitric acid is added to amine solution, solution is made acidic and the complex $$ion$$  dissociates and liberate silver ion to recombine with chloride $$ion.$$  This is the conformatory test for silver in group 1.