Balance the following equations and state whether the reacti…

Balance the following equations and state whether the reaction is a decomposition, single displacement, synthesis or double displacement reaction.  a)   HgO  –>  Hg   + O2  b)   Sr(OH)2  + Na2SO4 –> SrSO4  +  NaOH   c)   Mg  + HCl  –>  H2   +  MgCl