Given below are two statements :
Statement I : The decrease in first ionization enthalpy from B to Al is much larger than that from Al to Ga.
Statement II : The d orbitals in Ga are completely filled.
In the light of the above statements, choose the most appropriate answer from the options given below

Options

A. Both the statements I and II are incorrect
B. Statement I is correct but statement II is incorrect
C. Statement I is incorrect but statement II is correct
D. Both the statements I and II are correct

Answer

To solve the question, we need to analyze both statements regarding ionization enthalpy and the electronic configuration of gallium.

### Step-by-Step Solution:

1. **Understanding Ionization Enthalpy**:
- Ionization enthalpy is the energy required to remove an electron from an atom in the gaseous state. Generally, ionization enthalpy decreases down a group in the periodic table due to the increase in atomic size and the shielding effect.

2. **Comparing Boron (B) and Aluminum (Al)**:
- Boron (B) has the electronic configuration of \(1s^2 2s^2 2p^1\) and Aluminum (Al) has \(1s^2 2s^2 2p^6 3s^2 3p^1\).
- The increase in size from B to Al is significant, leading to a larger decrease in ionization enthalpy.

3. **Comparing Aluminum (Al) and Gallium (Ga)**:
- Gallium (Ga) has the electronic configuration of \(1s^2 2s^2 2p^6 3s^2 3p^1 3d^{10} 4s^2 4p^1\).
- The addition of the d-orbitals in Ga does not significantly increase the atomic size compared to Al. Therefore, the decrease in ionization enthalpy from Al to Ga is not as large as from B to Al.

4. **Evaluating Statement I**:
- Statement I claims that the decrease in first ionization enthalpy from B to Al is much larger than from Al to Ga. This is correct based on the reasoning above.

5. **Evaluating Statement II**:
- Statement II states that the d orbitals in Ga are completely filled. In Ga, the 3d orbitals are indeed filled (\(3d^{10}\)).
- This statement is also correct.

6. **Conclusion**:
- Both statements are correct. Therefore, the answer to the question is that both Statement I and Statement II are correct.

### Final Answer:
Both Statement I and Statement II are correct.