Statement 1 : Aliphatic amines are weaker bases than ammonia and aromatic amines are stronger bases than ammonia.Statement 2 : +I-effect of alkyl groups on aliphatic amines increase the electron density on nitrogen atom. Aromatic amines are weaker due to electron withdrawing nature of the aryl group.

Aliphatic amines are stronger base than ammonia due to +/-effect of alkyl groups leading to high electron density on the nitrogen atom.Their pKb values lie in the range of 3 to 4.22- Which is lower than pKb value of NH3, i.e. 4.75. On the other hand, aromatic amines are weaker base than ammonia due to the electron withdrawing nature of the aryl group.