What is +I and -I effect?
Kindly refer to the following link:
https://www.meritnation.com/ask-answer/question/explain-resonance-effect-inductive-effect-and-hypercongugati/chemistry/6275485
https://www.meritnation.com/ask-answer/question/explain-resonance-effect-inductive-effect-and-hypercongugati/chemistry/6275485