law: Indian Contract Act, 1872 
  36. Agreements contingent on impossible
  
  events, void 
  Contingent agreements to do or not to do anything, if an
  
  impossible event happens, are void, whether the impossibility of the event is
  
  known or not to the parties to the agreement at the time when it is made.
  Illustrations
  (a) A agrees to pay B 1,000 rupees if two straight lines should
  
  enclose a space. The agreement is void.
  (b) A agrees to pay B 1,000 rupees if B will marry A's daughter
  
  C. C was dead at the time of the agreement. The agreement is void.