14. Which of the following is not a nucleophile? A) HO B) CH3O C) NH3 (D) NH4 15. Which is the strongest nucleophile? A) OH B) CH3CHO C) All are nucleophiles. CH3CO D) CH3CHOH E) HO 16. Which is not a polar aprotic solvent? A) H3C B) H3C- C) D) E) H3C H O=0 CH3 -CEN CH3 CH3 CH3 CH3 _CH_ H3C OH 17. Of the following, which one is the best leaving group? A) F B) Cl C) Br D) I E) All of these are equally good LG. 18. Which nucleophilic substitution reaction would be unlikely to occur? A) HO + CH3CH2-I CH3CH-OH + I B) I + CH3CH2-H CH3CH-I + H CH3S-CH3 + Br C) CH3S + CH3-Br D) All of the above would be unlikely to occur. E) None of the above would be unlikely to occur.