Question

Arrange the following groups
$-F,-OH,-N{H}_2$ in the increasing order of their $-I$ effect.

• A. $-N{H}_2<-F<-OH$
• B. $-N{H}_2<-OH<-F$
• C. $-OH<-F<-N{H}_2$
• D. $-F<-N{H}_2<-OH$

Answer 1

The correct option is B $-N{H}_2<-OH<-F$

$-I$ effect depends on the electronegativity of the element .
More the electronegativity, more is the electron withdrawing power and more is the $-I$ effect shown by that particular group.
Here, fluorine, oxygen and nitrogen are of same period.
Along the period , when we move from left to right, the electronegativity generally increases.
Electronegativity follows the order
Nitrogen<Oxygen<Fluorine
So the $-I$ effect will follow the same order i.e.
$-N{H}_2<-OH<-F$