Unhindered amines attacking $\mathrm{CH}{}_3\mathrm{I}$ in the same solvent follow nucleophilicity that tracks basicity. The pKa values of the conjugate acids are: $\mathrm{CH}{}_3\mathrm{NH}{}_3{}^{+}$ 10.6; $\mathrm{NH}{}_4{}^{+}$ 9.25; $\mathrm{CF}{}_3\mathrm{CH}{}_2\mathrm{NH}{}_3{}^{+}$ 5.7; $p\text{-}\mathrm{O}{}_2\mathrm{N}-\mathrm{C}{}_6\mathrm{H}{}_4-\mathrm{NH}{}_3{}^{+}$ 1.0. The order of decreasing nucleophilicity of the free amines is

1. Amethylamine > 2,2,2-trifluoroethanamine > ammonia > 4-nitroaniline
2. Bmethylamine > ammonia > 2,2,2-trifluoroethanamine > 4-nitroaniline
3. Cammonia > methylamine > 2,2,2-trifluoroethanamine > 4-nitroaniline
4. D4-nitroaniline > 2,2,2-trifluoroethanamine > ammonia > methylamine