Cu does not liberate hydrogen gas when it reacts with dilute mineral acids because copper is less reactive and cannot displace hydrogen from dilute acids.
However, copper has a positive electrode potential, which means it is less likely to lose electrons and participate in such reactions, but this does not directly explain the inability to liberate hydrogen gas.
Step 2:
Thus, Assertion (A) is false, and Reason (R) is true, but they are not logically connected.