(ch3)2chch2oh__h2so4__ = a __hbr__= = c

CH3-CH-CH2OH (H2SO4,t)= CH3-C=CH2 + H2O

            |                                                   |

         CH3                                             CH3

CH3-C(CH3)=CH2+ HBr=CH3-C(CH3)-CH3

                                                           |

                                                          Br

CH3-C(CH3)-CH3 + NaOH=CH3-C(CH3)-CH3  +NaBr

          |                                                   |

         Br                                                OH