Question

how to find basicity of compound:
1 CH3--CH2--NH2
2 (CH3)2 NH

Answer 1

Basicity of the amines is defined by number and size of the alkyl groups attached to the nitrogen atom. In general, alkyl groups make the amine more basic because they shift electron density to the nitrogen in the amine. Alkyl group is larger than hydrogen atom. So, amine with a few alkyl groups will be less basic than amine with only one alkyl group.
So, primary amine is more basic than secondary amine, and secondary amine is more basic then tertiary amine.
1 CH3--CH2--NH2 (ethylamine) is more basic, than 2 (CH3)2NH (dymethylamine).