According to second law of thermodynamics

  a)     All heat can be converted into work
  b)     The efficiency of a heat engine is always lesser than unity

  c)     It is not possible to transfer heat from lower to higher temperature by it self

 

As per the II^nd law of thermodynamics It is impossible for a heat engine to convert the entire heat absorbed from the source into work. Also it states we can't transfer net heat from lower temperature to higher temperature without addition of work.