Identify the gas that is evolved when magnesium and manganese react with nitric acid.

Hydrogen gas is evolved when magnesium and manganese react with very dilute nitric acid. Nitric acid is generally a strong oxidizing agent, which usually oxidizes the hydrogen produced in a reaction into water and itself gets reduced to nitrogen oxides. However, magnesium and manganese are unique because they can react with very dilute nitric acid to liberate hydrogen gas. The chemical equation for magnesium is: Mg + 2HNO3(very dilute) → Mg(NO3)2 + H2↑.