In $$\begin{gathered} -{\mathrm{NO}}_2,-{\mathrm{NH}}_2,-{\mathrm{SO}}_3\mathrm{H} \\ \left(\mathrm{I}\right) \left(\mathrm{II}\right) \left(\mathrm{III}\right) \end{gathered}$$
The decreasing order of -I effect is

NO₂ is the most electronegative group and it has strong –I effect. After that SO₃H comes because S is less electronegative than N. NH₂ is an electron donating group and show + I effect