Which of the following is definitely true, if for a reaction activation energies of forward and backward reactions are equal?

Options

A. `DeltaH = 0`
B. `DeltaG = 0`
C. There is no catalyst
D. The order is zero

Answer

To solve the question, we need to analyze the relationship between the activation energies of the forward and backward reactions and the enthalpy change of the reaction.

### Step-by-Step Solution:

1. **Understand Activation Energy**:
- Activation energy (Ea) is the minimum energy required for a chemical reaction to occur. Each reaction has a forward activation energy (Ea_forward) and a backward activation energy (Ea_backward).

2. **Given Condition**:
- The problem states that the activation energies of the forward and backward reactions are equal:
\[ Ea_{\text{forward}} = Ea_{\text{backward}} \]

3. **Enthalpy Change Relation**:
- The enthalpy change (ΔH) for a reaction can be expressed in terms of the activation energies:
\[ \Delta H = Ea_{\text{forward}} - Ea_{\text{backward}} \]

4. **Substituting the Given Condition**:
- Since we know that \(Ea_{\text{forward}} = Ea_{\text{backward}}\), we can substitute this into the enthalpy change equation:
\[ \Delta H = Ea_{\text{forward}} - Ea_{\text{forward}} = 0 \]

5. **Conclusion**:
- The enthalpy change (ΔH) for the reaction is zero, which indicates that there is no net heat change during the reaction. This means the reaction is thermodynamically neutral in terms of energy.

### Final Answer:
- The statement that is definitely true if the activation energies of the forward and backward reactions are equal is:
- **The enthalpy change for the reaction is 0.**