Question: The standard free energy of activation of a reaction is: 
 Options:  <1> The difference in free energy between the basal state of the products and the substrates. <2> The difference of the enthalpy minus the entropy of the system. <3> The basal energy of the substrates in a catalyzed reaction. <4> The additional free energy that molecules must reach to reach the state of transition. <5> The energy released from a catalysed reaction.
4