When ash, cinders, and bombs build up in a steep pile around a volcano’s vent, the result is a
a. cinder cone volcano.
b. shield volcano.
c. composite volcano.
d. dormant volcano.

These form a composite volcano. Cindercones are mostly ash. Shields spew mostly lava. Composites combine ash, cinders, and bombs (large pieces of rock) into the steep form we typify as a volcano.

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