Answer : The another name for the activation energy barrier in a reaction is, Transition state.
Step-by-step explanation:
Activated complex : It is defined as when the molecules of reactants absorb energy then they loose their bonds and new bonds are formed between them. The intermediate thus formed is called as activated complex or transition state. It is an unstable state and immediately dissociates to form the stable products.
Activation energy : It is the minimum amount of energy absorbed by the reactant molecules so that their energy becomes equal to the threshold energy.
Activation energy barrier : It is the energy barrier that separates the energy levels of the reactants and products. The arrangement of atoms takes place at the peak of the activation energy barrier. That means the transition state is also known as the activation energy barrier.
The graph of energy is shown below.