Question

Arrange the following in the increasing order of basicity:

${CH}_3{NH}_2,{\left({CH}_3\right)}_{2}NH,{\left({CH}_3\right)}_{3}N$

Answer 1

In the gas phase, the increasing order of basicity is
$N{H}_3<{CH}_3{NH}_2<{\left({CH}_3\right)}_{2}NH<{\left({CH}_3\right)}_{3}N$
Note:
In the gas phase, the increasing order of basicity is

Ammonia < primary amine < secondary amine < tertiray amine.

The +I effect of alkyl groups increases electron density on N atom.
It increases the basicity of amines.