wht is +m effect???

Hiiii Prateek ! 

M-effect is termed as Mesomeric effect ...it is also alternatively termed as resonance effect ...It is a effect due to which a group attached with a resonating structure perfoms an electron withdrawing or releaising phenomenon...

And thus due to elctron withdrawing and realeasing this M effect is divided in two groups....

~ +m effect : Means the substituent will have electron releasing property

~-m effect : Means ...the substituent will have electron withdrawing property ...

Example : +NO2 has    + m effect...means...If on any compound it is attached as a substituent....then due to this NO2+ ..electron density in that compound will increase...because it has electron releasing property...

I hope it is clear

regards

Yagya

askiitians_expert