The general electronic configuration of outer most and penultimate shell is given as `(n-1)s^2(n-1)p^6(n-1)d^x ns^2`. Then for an element with `n = 4` and `x = 7`
The number of protons present in the divalent cation of the element of above configuration is 

Options

A. 25
B. 26
C. 27
D. 28

Answer

To solve the problem, we need to determine the number of protons present in the divalent cation of an element with the given electronic configuration `(n-1)s^2(n-1)p^6(n-1)d^x ns^2`, where `n = 4` and `x = 7`.

### Step-by-Step Solution:

1. **Identify the Value of n**:
Given that `n = 4`, we will substitute this value into the electronic configuration.

2. **Substitute n and x into the Configuration**:
The electronic configuration becomes:
- For `n = 4`:
- `(n-1)s^2` becomes `3s^2`
- `(n-1)p^6` becomes `3p^6`
- `(n-1)d^x` becomes `3d^7`
- `ns^2` becomes `4s^2`
- Therefore, the complete electronic configuration is:
\[ 3s^2 3p^6 3d^7 4s^2 \]

3. **Determine the Total Number of Electrons**:
- The total number of electrons in this configuration can be calculated as follows:
- From `3s^2`: 2 electrons
- From `3p^6`: 6 electrons
- From `3d^7`: 7 electrons
- From `4s^2`: 2 electrons
- Total = \(2 + 6 + 7 + 2 = 17\) electrons.

4. **Calculate the Atomic Number**:
- The atomic number (Z) of an element is equal to the number of protons in a neutral atom, which is also equal to the number of electrons in a neutral atom.
- Therefore, the atomic number of the element is 17, meaning it has 17 protons.

5. **Determine the Number of Protons in the Divalent Cation**:
- A divalent cation means that the element has lost 2 electrons.
- Therefore, the number of protons remains the same, which is 17.

### Final Answer:
The number of protons present in the divalent cation of the element is **17**.