Why are the secondary amines more basic than primary amines?
Amines are bases due to the lone pair of electrons on the nitrogen atom of amines. These react with water to form hydroxyl ions.
Bases are those species that donate OH- ions (hydroxyl ions). The more easily is the availability of the hydroxyl ions; more is the basicity of the amine. A secondary amine can donate its lone pair more easily, as the extra inductive effect stabilises the charge on the nitrogen atom