Ageologist is someone who studies geography studies the earth studies germs

A geologist does not study germs: A geologist is focused on the rocks on earth, and germs are not rocks, but living organisms.

In a way, the other two options : "the Earth" and "geography" are both correct and they are the same: Geography is the study of the Earth, including the organisms living on it.

If we understand "the Earth" to mean only the physical Earth - then this is the correct answer.

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

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