Statement 1: ${\mathrm{N}}_3^{-}$ is a weaker base than ${\mathrm{NH}}_2^{-}$

Statement 2: The lone pair of electrons on N atom in ${\mathrm{N}}_3^{-}$ is in a sp²-orbital while in ${\mathrm{NH}}_2^{-}$ it is in an sp³-orbital.

Basicity depends upon availability of lone pair of electrons. Since ${\mathrm{N}}_3^{-}$ is in SP² - orbital, its lone pair is less available as compared to ${\mathrm{NH}}_2^{-}$ . Thus, ${\mathrm{N}}_3^{-}$ is a weaker base than ${\mathrm{NH}}_2^{-}$ .