3.Draw stable conformations for the following compounds(12). a b Ph F-H 〉F十Newmann ProjectB Ph Ph H Pn 3.Write stepwise and reasonable mechanisms for the following reactions(20) 1.Predict major product and write mechanism. 人 Br2 hvBr +'Br ·Br+Br→Br2 人B一人 +人r 购+人一”+B 人·人X 2火Br+EOH0e Xa一人一k业，思 ee·& 2 2 3. Draw stable conformations for the following compounds (12). H H Br H Ph F Ph F H a b c Newmann Project a b H F Ph F H Ph c Br 3. Write stepwise and reasonable mechanisms for the following reactions (20) 1. Predict major product and write mechanism. Br2, hv Br2 hν Br + Br Br + Br Br2 + Br + HBr Br + Br + Br Br2 + + Br . Br + EtOH 2. OEt Br HOEt O H Et - H OEt Et O H H OEt HOEt