Chemistry - GOC Question with Solution | TestHub

The decreasing order of -I effect of the following is:

$\text{I}\text{.}-\stackrel{\oplus }{\text{N}}{\text{H}}_{\text{3}}\text{II}\text{.}-N{O}_2\text{III}\text{.}-\text{CN}\text{IV}\text{.}-\text{COOH}$