Why does mercury not produce hydrogen gas when treated with dilute acids?

Mercury does not produce hydrogen gas when treated with dilute acids because it has a positive reduction potential, making it inert toward the aqueous hydrogen ion.1

In chemistry, metals with negative reduction potentials can, in principle, displace hydrogen from strong acid solutions. For example, zinc, which has a negative reduction potential of −0.763 volt, reacts with hydrogen ions to produce hydrogen gas. Conversely, metals with positive reduction potentials, such as silver (+0.7995 volt), are inert toward hydrogen ions. Mercury is anomalous among the zinc group elements in this regard; while zinc and cadmium readily produce hydrogen upon treatment with dilute acids, mercury does not.12