Better method for preparation of `BeF_2`, among the following is

Options

A. `BeH_2 + F_2 overset(Delta)rightarrow BeF_2`
B. `BeO + C+ F_2 overset(Delta)rightarrow BeF_2`
C. `(NH_4)_2BeF_4 overset(Delta)rightarrow BeF_2`
D. `Be + F_2 overset(Delta)rightarrow BeF_2`

Answer

To solve the question regarding the better method for the preparation of beryllium fluoride (BeF₂), we will analyze the given reactions and identify the most efficient one.

### Step-by-Step Solution:

1. **Understanding the Compounds**:
- We need to prepare beryllium fluoride (BeF₂).
- Beryllium (Be) is a metal, and fluoride (F) is derived from fluorine.

2. **Analyzing the Given Reactions**:
- We have four reactions to consider, but we will focus on the third reaction as mentioned in the video transcript.

3. **Identifying the Third Reaction**:
- The third reaction involves the thermal decomposition of ammonium fluoride (NH₄F) to produce beryllium fluoride (BeF₂) and other products.
- The reaction can be represented as:
\[ 2 \text{NH}_4\text{F} + \text{Be} \rightarrow \text{BeF}_2 + \text{other products} \]

4. **Balancing the Reaction**:
- To ensure the reaction is balanced, we need to confirm that the number of atoms of each element is the same on both sides of the equation.
- For this reaction, we can balance it as follows:
\[ 2 \text{NH}_4\text{F} \rightarrow \text{BeF}_2 + \text{other products} \]
- Here, we see that we have 2 nitrogen (N), 8 hydrogen (H), and 2 fluorine (F) on the left side, which balances with the products.

5. **Conclusion**:
- The thermal decomposition of ammonium fluoride is an effective method to produce beryllium fluoride.
- Therefore, the better method for the preparation of BeF₂ is the third option.

### Final Answer:
The better method for the preparation of BeF₂ is the third reaction involving the thermal decomposition of ammonium fluoride.

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