Find the total number of molecules and atoms in the reactants:
N2+3H2→2NH3
Molecules - 4
Atoms - 8
In the given chemical equation, N2+3H2→2NH3 the reactants are N2+3H2.
Number of molecules on reactant side = 4
( 1 molecule of N2 + 3 molecules of H2)
Number of atoms on reactant side = 8
(2 atoms of nitrogen + 6 atoms of hydrogen)