Answer:
C
Explanation:
If the enthalpy change (i.e. ΔH) of a reaction is negative, then the reaction releases heat and is hence exothermic.
Hence, our answer is C.
Conversely, if ΔH is positive, the reaction absorbs heat and is endothermic.
ΔH tells us nothing about the speed of the reaction.
While ΔH influences free-energy change (ΔG = ΔH - TΔS), we cannot predict the sign of ΔG given only ΔH (recall that a reaction is spontaneous if ΔG < 0).
