system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Activation energy is free energy difference between the ____:
assistant
The correct answer is  Activation energy is free energy difference between the substrate & transition state.
Activation energy may be also be defined as the minimum energy required to start a chemical reaction.
Reference-Harper 30th edition pg -75