Platinum and gold lies at the bottom of the reactivity series. Thus it does not react with 𝐻𝑁𝑂3 and 𝐻𝐶𝑙. Again, 𝑍𝑛 is more reactive than copper. Thus, copper will be displaced by 𝑍𝑛, if 𝑍𝑛𝑆𝑂4 is placed in a copper vessel. But 𝐴𝑔+ is less reactive than copper. Thus, copper will displace silver. The corresponding reaction is: 2𝐴𝑔𝑁𝑂3+𝐶𝑢→𝐶𝑢(𝑁𝑂3)2+2𝐴g