Answer:
1) Activation energy
2) Internal energy
Explanation:
A reaction takes place is the reactants have a certain minimum amount of energy known as threshold energy.
All the reactants have some inherent energy known as internal energy, which corresponds to the potential, kinetic, vibrational, roational etc energy of the substance.
The rest amount of energy required by the reactants is known as activation energy. This the minimum extra amount of energy required to reach or cross the threshold energy level.
