Most of the earth���s freshwater is located in
a. icecaps and glaciers
b. north america
c. rivers and lakes
d. the world���s oceans

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

According to new research, more than 5..5 million deaths are associated with polluted air. hope this : ).

Poaching of all these specific species

1. why do astronomers think that there may be other advanced civilizations?
because  it was discovered that there are other planets like earth out there, able to  accommodate life forms.
2. what technologies are astronomers using to look for life on other planets? why?  
they  have used radio telescopes, but now they use laser telescopes   to track laser communications.