Diborane can't be obtained from

Options

A. `Na_(2) B_(4) O_(7) + HCl`
B. `NaBH_(4) + I_(2)`
C. `BF_(3) + l iAlH_(4)`
D. `BF_(3) + NaH`

Answer

To determine from which reaction diborane (B2H6) cannot be obtained, we will analyze each of the given options step by step.

### Step-by-Step Solution:

1. **Identify the Chemical Formula of Diborane**:
- Diborane is represented by the chemical formula B2H6.

2. **Analyze Each Option**:
- **Option 1**: Reaction of Sodium Tetraborate (Na2B4O7) with Hydrochloric Acid (HCl).
- The reaction produces boric acid (H3BO3) and sodium chloride (NaCl).
- No diborane is formed in this reaction.
- **Conclusion**: Diborane is NOT obtained from this reaction.

- **Option 2**: Reaction of Sodium Borohydride (NaBH4) with Iodine (I2).
- The reaction produces diborane (B2H6), sodium iodide (NaI), and hydrogen gas (H2).
- **Conclusion**: Diborane IS obtained from this reaction.

- **Option 3**: Reaction of Boron Trifluoride (BF3) with Lithium Aluminum Hydride (LiAlH4).
- The products include lithium fluoride (LiF), aluminum trifluoride (AlF3), and diborane (B2H6).
- **Conclusion**: Diborane IS obtained from this reaction.

- **Option 4**: Reaction of Boron Trifluoride (BF3) with Sodium Hydride (NaH).
- This reaction also produces diborane (B2H6) along with sodium fluoride (NaF).
- **Conclusion**: Diborane IS obtained from this reaction.

3. **Final Conclusion**:
- Among the options analyzed, diborane cannot be obtained from the reaction of sodium tetraborate with hydrochloric acid (Option 1).

### Answer:
Diborane can't be obtained from the reaction of sodium tetraborate with hydrochloric acid.