How long ago did oceans begin to form? 12.5 MYA. 137 MYA. 285 MYA. 3800 MYA.

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen

Answer( solar wind );