The activation energy for a(n) is quite large and usually takes extra energy from the environment, it is normally not a natural spontaneous process. combustion reaction endothermic reaction exothermic reaction catalyzed reaction

The given blank can be filled with endothermic reactions.  

The endothermic reactions or processes captivates energy from its surroundings, primarily, but will not always be in the form of heat. A reaction, which requires the input of energy that dissociates a bond will always be endothermic. The best examples of endothermic reactions are evaporation of the liquid, melting cubes, melting or solid salts, and others.  

d.) the average kinetic energy of the gas particles is greater in container b because its particles move faster.