Inductive effect

Inductive effect is a permanent electronic displacement and also known as "Transmission effect".

→ Where I - effect takes place ?

        In σ - bonded organic compound where electronegativity of atoms didfferent. Due to            elecronagetivity difference I - effect occur.

        Consider compound AB where B is more electronegative than A . Therefor σ - bond polarization occur. It is depicted as below, 

                                                     A  ー>ー  B

        It is distance dependent factor and its influence have upto 3 or 4 atoms.

→ Types of I - effect :

         + I - effect and - I - effect 

         In + I - effect group or atom electron release towards chain while in - I - effect group or atom electron pool or accept from the carbon chain in organic compound.

         You can check order of + I and - I effect for different groups or atoms from below link ,

          https://chemstudy2017.blogspot.com/2018/12/l-ist-of-electron-withdrawing-i-and.html

 
         For solve examples apply DNP rule. D for Distance , N for number of groups or atoms and P for power. First check distance of group or atom.if distance is same for groups or atoms than consider number of groups or atoms. If both D and N are same than last check power of groups or atoms.