Arrange the basicity of the given compounds in decreasing order

1)${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{NH}}_2$

2)${\mathrm{CH}}_2=\mathrm{CH}-{\mathrm{NH}}_2$

3)$\mathrm{HC}\equiv \mathrm{C}-{\mathrm{NH}}_2$

In a carbon compound, if the amine group $-{\mathrm{NH}}_2$ is attached to C-C bond ( ${\mathrm{sp}}^3$ ) then it is more basic than $\mathrm{C}=\mathrm{C}$  ( ${\mathrm{sp}}^2$ ) and $\mathrm{C}\equiv \mathrm{C}$ (sp)

Because alkenes and alkynes are electron deficient molecules.

1)${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{NH}}_2$ 2)${\mathrm{CH}}_2=\mathrm{CH}-{\mathrm{NH}}_2$

3)$\mathrm{HC}\equiv \mathrm{C}-{\mathrm{NH}}_2$

If an amino group is attached to C-C (in alkanes), its basicity is high. Therefore, the decreasing order of basicity is $1>3>2$