The isotopes of hydrogen have different physical properties due to difference in mass. They have almost same chemical properties with a difference in their rates of reactions which is mainly due to

Options

A. their different enthalpy of bond dissociation
B. different electronic configurations
C. different atomic masses
D. different physical properties.

Explanation

To solve the question regarding the isotopes of hydrogen and their differing rates of reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Isotopes**:
- Isotopes of hydrogen include protium (¹H), deuterium (²H), and tritium (³H). They have the same number of protons but different numbers of neutrons, leading to different atomic masses.

2. **Physical vs. Chemical Properties**:
- While isotopes have different physical properties (like mass), their chemical properties are largely similar because they have the same electronic configuration. This means they participate in chemical reactions in a similar manner.

3. **Rate of Reaction**:
- The question specifically asks about the difference in rates of reaction among these isotopes. The rate of reaction can be influenced by the mass of the isotopes due to kinetic isotope effects.

4. **Analyzing the Options**:
- **Option A: Different enthalpy of bond dissociation** - This is a valid point. The bond dissociation energy varies between isotopes, which affects the rate of reaction.
- **Option B: Different electronic configuration** - This is incorrect as all isotopes of hydrogen have the same electronic configuration.
- **Option C: Different atomic masses** - While atomic mass is different, it does not directly explain the difference in rates of reaction.
- **Option D: Different physical properties** - This option is also incorrect as physical properties do not influence chemical reaction rates.

5. **Conclusion**:
- The correct answer is **Option A: Different enthalpy of bond dissociation**. The difference in bond dissociation energy leads to varying rates of reaction among the isotopes.

### Final Answer:
The rate of reaction of isotopes of hydrogen differs mainly due to **different enthalpy of bond dissociation**.

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