`""_(8)^(x)X` atom is isotone to `""_(9)^(17)Y` atom. The value of x is

Options

A. 8
B. 16
C. 9
D. 17

Answer

To solve the problem, we need to find the value of \( x \) for the atom represented as \( _{8}^{x}X \) that is isotone with the atom \( _{9}^{17}Y \).

### Step-by-Step Solution:

1. **Understanding Isotones**:
- Isotones are atoms that have the same number of neutrons but different numbers of protons.

2. **Identify the Given Information**:
- For the atom \( _{8}^{x}X \):
- Atomic number (Z) = 8
- Atomic mass (A) = \( x \)
- For the atom \( _{9}^{17}Y \):
- Atomic number (Z) = 9
- Atomic mass (A) = 17

3. **Calculate the Number of Neutrons**:
- The number of neutrons (N) can be calculated using the formula:
\[ N = A - Z \]
- For \( _{8}^{x}X \):
\[ N_X = x - 8 \]
- For \( _{9}^{17}Y \):
\[ N_Y = 17 - 9 = 8 \]

4. **Set the Number of Neutrons Equal**:
- Since \( _{8}^{x}X \) and \( _{9}^{17}Y \) are isotones, we set their neutron counts equal:
\[ x - 8 = 8 \]

5. **Solve for \( x \)**:
- Rearranging the equation gives:
\[ x = 8 + 8 = 16 \]

6. **Conclusion**:
- The value of \( x \) is 16.

### Final Answer:
The value of \( x \) is \( 16 \).