Question

Hydrogen gas is not evolved when most metals react with nitric acid'. State reasons to justify this statement.

Answer 1

When metals react with nitric acid hydrogen gas is liberated.

Nitric acid is a very strong oxidizing agent.

So , it oxidizes the hydrogen gas formed during the reaction to form water and an oxide of nitrogen (NO,N2O,NO2 etc.).

The reaction for it is:-

Zn+4HNO3→Zn(NO3)2+2NO2+2H2O

Exception:-
Magnesium and manganese react with very dilute nitric acid to liberate hydrogen gas.

The reaction for it is:-

Mg+2HNO3→Mg(NO3)2+H2

Answer 2

When metals react with nitric acid hydrogen gas is liberated.

Nitric acid is a very strong oxidizing agent.

So , it oxidizes the hydrogen gas formed during the reaction to form water and an oxide of nitrogen (NO,N2O,NO2 etc.).

The reaction for it is:-

Zn+4HNO3→Zn(NO3)2+2NO2+2H2O

Exception:-

Magnesium and manganese react with dilute nitric acid to liberate hydrogen gas.

The reaction is:-

Mg+2HNO3→Mg(NO3)2+H2O