Hbr addition to an alkene is a ch221 reaction with which you should be familiar. when peroxides are present, one regioisomer is observed while in the absence of peroxides, the other regioisomer is observed. two separate hbr addition reactions are carried out using the same starting alkene whose molecular formula is c5h10. one was carried out in the presence of peroxides and the other in the absence of peroxides. use the nmr spectra to decide which addition product was obtained from each reaction. nmr for product from first reaction whose molecular formula is c5h11br.