Lithium aluminium hydride can be prepared from the reaction of :

Options

A. `LiH` and `Al(OH)_(3)`
B. `LiCl` and `Al_(2)H_(6)`
C. `LiClAl` and `H_2`
D. `LiH` and `Al_2Cl_(3)`

Answer

To solve the question regarding the preparation of lithium aluminium hydride (LiAlH4), we need to analyze the given options and identify the correct reactants that lead to the desired product.

### Step-by-Step Solution:

1. **Understanding the Components**:
- Lithium aluminium hydride (LiAlH4) is a compound that contains lithium (Li), aluminum (Al), and hydrogen (H).
- We need to find a reaction that produces LiAlH4 from the provided options.

2. **Analyzing the Options**:
- **Option 1**: LiH and Al(OH) - This option does not seem to provide the necessary aluminum and hydride ions to form LiAlH4.
- **Option 2**: LiCl and Al2Cl6 - This option involves lithium chloride and aluminum chloride, but does not directly lead to the formation of hydride.
- **Option 3**: LiCl, Al, and H2 - This option includes aluminum and hydrogen gas, but it does not directly yield LiAlH4.
- **Option 4**: LiH and Al2Cl3 - This option involves lithium hydride and aluminum chloride, which can react to produce LiAlH4.

3. **Identifying the Correct Reaction**:
- The correct reaction for the preparation of lithium aluminium hydride is:
\[ 3 \text{LiH} + \text{Al}_2\text{Cl}_6 \rightarrow 2 \text{LiAlH}_4 + 6 \text{LiCl} \]
- This reaction shows that lithium hydride reacts with aluminum chloride (specifically, the dimer Al2Cl6) to produce lithium aluminium hydride and lithium chloride.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option 4: LiH and Al2Cl3**.