In which of the following periods of the mesozoic era did a bird-like animal known as archaeopteryx appear? a. triassic b. jurassic c. cambrian d. cretaceous

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

Answerair masses develop near the equator are warm; tropical air mass