The electronic configuration of a dipositive ion M2+ is 2,8,14 and its mass number is 56. What is the number of neutrons present?

Options

A. 32
B. 42
C. 30
D. 34

Explanation

To find the number of neutrons present in the dipositive ion M²⁺ with a given electronic configuration and mass number, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electronic Configuration**: The electronic configuration given is 2, 8, 14. This means that the ion has:
- 2 electrons in the first shell
- 8 electrons in the second shell
- 14 electrons in the third shell

2. **Calculate the Total Number of Electrons**:
- Total electrons = 2 + 8 + 14 = 24 electrons.

3. **Determine the Atomic Number (Z)**:
- For a neutral atom, the number of protons is equal to the number of electrons. However, since we have a dipositive ion (M²⁺), it has lost 2 electrons.
- Therefore, the number of protons (atomic number Z) = Total electrons + 2 = 24 + 2 = 26.

4. **Use the Mass Number to Find Neutrons**:
- The mass number (A) is given as 56.
- The number of neutrons (N) can be calculated using the formula:
\[ N = A - Z \]
- Substituting the values we have:
\[ N = 56 - 26 = 30 \]

5. **Conclusion**:
- The number of neutrons present in the dipositive ion M²⁺ is 30.

### Final Answer:
The number of neutrons present is **30**.

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