Aqua regia is a mixture of concentrated hydrochloric acid and concentrated nitric acid. It is prepared by mixing these two acids together in specific proportions.

Copper does not react with dilute nitric acid because it is less reactive compared to magnesium, manganese, aluminum, zinc, and iron. The lack of bubbles and unchanged temperature during the reaction with copper confirm that it does not react with ...

The rate of formation of bubbles when metals react with dilute nitric acid depends on the reactivity of the metal. More reactive metals like magnesium react faster and produce bubbles more rapidly compared to less reactive metals.

Magnesium and manganese react with very dilute nitric acid to evolve hydrogen gas because they are more reactive metals that can displace hydrogen from nitric acid, even in its oxidizing environment.

Hydrogen gas is not evolved when a metal reacts with nitric acid because nitric acid (HNO3) is a strong oxidizing agent. It oxidizes the hydrogen gas produced to water while itself getting reduced to various nitrogen oxides (N2O, NO, NO2).