According to the nuclear reaction `Be_4^x + He_2^4 to C_6^12 +n_0^1`, mass number of (Be) atom is

Options

A. 4
B. 9
C. 7
D. 6

Answer

To find the mass number of the beryllium atom in the given nuclear reaction \( \text{Be}_4^x + \text{He}_2^4 \rightarrow \text{C}_6^{12} + n_0^1 \), we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Components of the Reaction:**
- We have beryllium (\( \text{Be} \)), helium (\( \text{He} \)), carbon (\( \text{C} \)), and a neutron (\( n \)).
- The given reaction can be summarized as:
\[ \text{Be}_4^x + \text{He}_2^4 \rightarrow \text{C}_6^{12} + n_0^1 \]

2. **Write Down the Mass Numbers:**
- The mass number of beryllium is \( x \).
- The mass number of helium is \( 4 \).
- The mass number of carbon is \( 12 \).
- The mass number of the neutron is \( 1 \).

3. **Apply the Conservation of Mass Number:**
- According to the law of conservation of mass number, the total mass number on the reactant side must equal the total mass number on the product side.
- Therefore, we can set up the equation:
\[ x + 4 = 12 + 1 \]

4. **Simplify the Equation:**
- Calculate the right side:
\[ x + 4 = 13 \]

5. **Solve for \( x \):**
- Rearranging the equation gives:
\[ x = 13 - 4 \]
\[ x = 9 \]

6. **Conclusion:**
- The mass number of the beryllium atom is \( 9 \).

### Final Answer:
The mass number of the beryllium atom is \( 9 \).