Question

Why do metals do not evolve hydrogen gas with nitric acid?

Answer 1

Nitric acid(HNO3) is a strong oxidising agent.
The Hydrogen gas produced during its reaction with metal gets oxidised to H2O, hence no hydrogen gas is produced.
Instead it evolves nitric oxides such as  NO2,NO etc.

For Eg:
Cu(s) + 4HNO3(aq)--->Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l) 

Answer 2

$\underline{\underline{\Huge\mathfrak{Answer}}}$

When metals reacts with Nitric Acid. The Nitric Acid is a strong oxidizing agent. It oxidises Hydrogen evolved in the reaction to water and itself is reduced to an oxide of Nitrogen. It may be Nitrous oxide, Nitric Oxide or Nitrogen Dioxide. Thus, Hydrogen gas is not evolved.

$Zn(s)+4HNO_{3}(aq)\xrightarrow{}}Zn(NO_{3})_{2}(aq)+2H_{2}O(l)+2NO_{2}(g)$