For each of the following substituents, indicate whether it withdraws electrons inductively, donates electrons by hyperconjugation, withdraws electrons by resonance, or donates electrons by resonance. (Effects should be compared with that of a hydrogen; remember that many substituents can be characterized in more than one way).
A. Br
1. Withdraws electrons inductively.
2. Donates electrons by hyperconjugation.
3. Withdraws electrons by resonance.
4. Donates electrons by resonance.
B. CH2CH3
1. Withdraws electrons inductively.
2. Donates electrons by hyperconjugation.
3. Withdraws electrons by resonance.
4. Donates electrons by resonance.
C. NHCH31. Withdraws electrons inductively.2. Donates electrons by hyperconjugation.3. Withdraws electrons by resonance.4. Donates electrons by resonance.D. OCH31. Withdraws electrons inductively.2. Donates electrons by hyperconjugation.3. Withdraws electrons by resonance.4. Donates electrons by resonance.E. +N(CH3)31. Withdraws electrons inductively.2. Donates electrons by hyperconjugation.3. Withdraws electrons by resonance.4. Donates electrons by resonance.

Halogens are electronegative elements hence they withdraw electrons by inductive effect. However, they also contain lone pairs so the can donate electrons by resonance.

Alkyl groups donate electrons by hyperconjugation involving hydrogen atoms.

-NHCH3 and contain species that have lone pair of electrons which can be donated by resonance. Also, the nitrogen and oxygen atoms are very electron withdrawing making the carbon atom to have a -I inductive effect.

+N(CH3)3 have no lone pair and is strongly electron withdrawing by inductive effects.