I've read in [Wikipedia](https://en.wikipedia.org/w/index.php?title=Mesomeric_effect&oldid=1011528450) about +M strength of groups which goes: > –O __-__ > –NH2 > __–NHCOR > –OR__ > –OCOR > –Ph > –CH3 > –F > –Cl > –Br > –I Now in every other website states that in terms of +M strength: [![enter image description here][1]][1] [website->brainly](https://brainly.in/question/10469471) [![enter image description here][2]][2] [website->Chemistry libretexts](https://chem.libretexts.org/Courses/Purdue/Purdue%3A_Chem_26200%3A_Organic_Chemistry_II_(Wenthold)/Chapter_15._Reactions_of_Aromatic_Molecules/15.03%3A_Substitution_effects_on_orientation/15.03.1%3A_Theory_of_Directing_effects) *(And many more)* # My question: # Can you please verify the series and explain the reason if -OR actually has less activity than -NHCOR? * Also since in -NH of -NHCOR there is an EWG(Electron withdrawing group) which is -COCH3 which should decrease the +M strength of the group appreciably. [1]: https://i.sstatic.net/woUlL.jpg [2]: https://i.sstatic.net/wh8g9.jpg