Identify the correct statements regarding the structure of `Al(BH_4)_(3)`.
1. Al is `sp^3d^2 and B` is `sp^3` hybridized
2. It has 6 `3c - 2e^-` bonds
3. It has 6 Al - H - B bonds
4. It has 6 `2c - 2e^-` bonds.

Options

A. only 1,3,4
B. only 1,2,3
C. only 1.24
D. all of 1, 2, 3 and 4

Answer

To solve the question regarding the structure of \( Al(BH_4)_3 \), we will analyze each statement one by one.

### Step 1: Determine the hybridization of Aluminium and Boron
- **Aluminium (Al)**: In \( Al(BH_4)_3 \), aluminium is surrounded by four \( BH_4^- \) groups. Each \( BH_4^- \) contributes one bond to aluminium, leading to a total of four sigma bonds. Additionally, aluminium can utilize its d-orbitals for bonding. Therefore, the hybridization of aluminium is \( sp^3d^2 \).
- **Boron (B)**: Each boron atom in \( BH_4^- \) is bonded to four hydrogen atoms, which means it forms four sigma bonds. Thus, the hybridization of boron is \( sp^3 \).

**Conclusion**: The first statement is correct: "Al is \( sp^3d^2 \) and B is \( sp^3 \) hybridized."

### Step 2: Count the number of 3-center 2-electron bonds
- In the structure of \( Al(BH_4)_3 \), each \( BH_4^- \) group forms a bond with aluminium and shares electrons with hydrogen. Each bond involving aluminium, boron, and hydrogen can be classified as a 3-center 2-electron bond.
- There are six such bonds in total, as each \( BH_4^- \) contributes one bond and there are three \( BH_4^- \) groups.

**Conclusion**: The second statement is correct: "It has 6 \( 3c - 2e^- \) bonds."

### Step 3: Analyze the number of Al-H-B bonds
- Each \( BH_4^- \) group contributes one \( Al-H-B \) bond. Since there are three \( BH_4^- \) groups, there are a total of six \( Al-H-B \) bonds.

**Conclusion**: The third statement is correct: "It has 6 Al-H-B bonds."

### Step 4: Count the number of 2-center 2-electron bonds
- The bonds between boron and hydrogen in each \( BH_4^- \) are classified as 2-center 2-electron bonds. Each \( BH_4^- \) has four such bonds (one for each \( B-H \)). Since there are three \( BH_4^- \) groups, there are a total of 12 \( 2c - 2e^- \) bonds.

**Conclusion**: The fourth statement is incorrect: "It has 6 \( 2c - 2e^- \) bonds." The correct number is 12.

### Final Answer
The correct statements regarding the structure of \( Al(BH_4)_3 \) are:
1. Al is \( sp^3d^2 \) and B is \( sp^3 \) hybridized.
2. It has 6 \( 3c - 2e^- \) bonds.
3. It has 6 Al-H-B bonds.

Thus, the correct option is **1, 2, and 3 only**.