A reddish brown metal does not react with dilute hydrochloric acid but the oxide of the same metal reacts with dilute hydrochloric acid to give a blue coloured solution. Identify the metal.

A reddish brown metal does not react with dilute hydrochloric acid but the oxide of the same metal reacts with dilute hydrochloric acid to give a blue coloured solution. The metal is copper.

Copper is a brown coloured metal which does not react with dilute hydrochloric acid as in the activity series copper is less reactive than hydrogen and hence cannot displace it from the acidic solution.

 But the oxide of the same metal reacts with dilute hydrochloric acid to give blue colored solution which can be shown as

$\mathrm{CuO} +2\mathrm{HCl}\to {\mathrm{CuCl}}_2+{\mathrm{H}}_2\mathrm{O}$