By what unit the oxidation number changes for underline elements in the following reaction-
Zn + HNO3 → NH4NO3 + Zn (NO3)2 + H2O
8 units
In HNO3 the oxidation state of N is +5 and the oxidation number of N is -3 in NH4NO3 hence there is change in oxidation number by 8 units.