Answer:
By adding, a few drops of AgNO3
Dilute HCl reacts with silver nitrate to give a white precipitate of silver chloride.
On the other hand there is no reaction observed when dilute Nitric acid is treated with silver nitrate solution. That is obvious
Reactions :-
HCl(aq) + AgNO3(aq) >>> AgCl(s) + HNO3(aq)
HNO3(aq) + AgNO3(aq) >>> No reaction + No precipitate