Upon the addition of heat energy to a system, which of the following is most likely to occur?
a. the temperature will decrease.
b. the mass of particles will increase.
c. the average kinetic energy of particles will increase.
d. the average kinetic energy of particles will decrease.

the best answer is C. 

why not A? we actually don't know if adding heat will decrease or increase temperature. we would need to know what type of reaction we have if it is endothermic or exothermic

Why not B? the mass of particles does not change that easily. occasions, when the masses change, is during nuclear decays.

Why not D? adding heat of a system gives energy to the particles. these will move faster and be doing so increases the kinetic energy.