On a topographic map, contour lines that are closer together indicate
a. roads.
b. forest.
c. a steeper slope.
d. a mountain top.

C. a steeper slope.  

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 the use of flood plains and irrigation;