The excess of energy required for the reactant molecules to undergo a reaction is

Options

A. Potential energy
B. Kinetic energy
C. Thermal energy
D. activation energy

Answer

To solve the question regarding the excess energy required for reactant molecules to undergo a reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concept of Activation Energy**:
- In chemical reactions, reactant molecules need a certain amount of energy to break their bonds and form new bonds to create products. This energy is known as activation energy.

2. **Identifying the Role of Activation Energy**:
- Activation energy is the minimum energy that must be provided to the reactants for the reaction to proceed. It is necessary to overcome the energy barrier for the reaction to occur.

3. **Analyzing the Options**:
- The question provides multiple choices: potential energy, kinetic energy, thermal energy, and activation energy. We need to identify which of these terms correctly describes the excess energy required for the reaction.

4. **Selecting the Correct Answer**:
- Among the options provided, "activation energy" specifically refers to the excess energy required for reactants to transform into products. Therefore, the correct answer is activation energy.

5. **Conclusion**:
- The excess energy required for the reactant molecules to undergo a reaction is termed as activation energy.

### Final Answer:
The excess energy required for the reactant molecules to undergo a reaction is **activation energy**.

---