Answer:
= 100kJ
Explanation:
The reverse reaction's activation energy of a reaction is the activation energy of the forward reaction plus ΔH of the reaction:
Ea of forward reaction =75kJ
∆H = -175 kJ/mol
Ea of reverse reaction = 75 +(-175)
= 100kJ
Note that a reverse reaction is one which can proceed in both direction depending on the conditions.