$\mathrm{R}_3 \mathrm{~N}<\mathrm{R}_2 \mathrm{NH}<\mathrm{R}-\mathrm{NH}_2<\mathrm{NH}_3$

$\mathrm{NH}_3<\mathrm{R}-\mathrm{NH}_2<\mathrm{R}_2 \mathrm{NH}<\mathrm{R}_3 \mathrm{~N}$

$\mathrm{R}_2 \mathrm{NH}<\mathrm{R}_3 \mathrm{~N}<\mathrm{R}-\mathrm{NH}_2<\mathrm{NH}_3$

$\mathrm{NH}_3<\mathrm{R}_3 \mathrm{~N}<\mathrm{R}_2 \mathrm{NH}<\mathrm{R}-\mathrm{NH}_2$