silver + acid

Only concentrated nitric acid can react with silver.
Concentrated nitric acid has strong oxidizing power to oxidize silver into silver ion. At the same time, it is reduced.
Chemical equation: Ag + 2H^+ + NO3^- ---> Ag^+ + NO2 + H2O

On the other hand, dilute sulphuric acid and concentrated hydrochloric acid only exhibit acidic property. Without strong oxidizing power as concentrated nitric acid, they are not able to oxidize silver into silver ion.