[By Lussac's law]
N21 vol.+:3H23 vol.⟶⟶2NH32 vol.
To calculate the volume of ammonia gas formed.
H2367.2:::NH32x
∴32×67.2=44.8 lit
Hence, volume of NH3 formed is 44.8 lit.
We know,
H2367.2:::N21x
∴31×67.2=22.4 lit
∴ nitrogen left = 44.8 - 22.4 = 22.4 lit.
Hence, 22.4 lit of nitrogen remains in the resultant mixture.