A transition element X has a configuration `3d^4` in its `+3` oxidation state. Its atomic number is not

Options

A. 25
B. 26
C. 22
D. 19

Answer

To solve the question, we need to identify the transition element X that has a `3d^4` electronic configuration in its `+3` oxidation state and determine which of the given atomic numbers does not correspond to this element.

### Step-by-Step Solution:

1. **Identify the Element with `3d^4` in `+3` Oxidation State**:
- The `3d` subshell can hold a maximum of 10 electrons. The `3d^4` configuration means that there are 4 electrons in the `3d` subshell.
- In the `+3` oxidation state, the element loses 3 electrons. Typically, electrons are removed from the outermost shell first (the `4s` subshell) before the `3d` subshell.

2. **Determine the Electron Configuration of the Element**:
- For an element to have a `3d^4` configuration in its `+3` oxidation state, it must have had a higher number of electrons before losing 3.
- The general electron configuration for transition metals is of the form `noble gas core + 4s^2 + 3d^x`.

3. **Calculate the Total Electron Count**:
- If the element has `3d^4` in the `+3` state, it must have had `3d^7` in its neutral state (since 4 + 3 = 7).
- The electron configuration of the neutral atom would be `4s^2 3d^7`.

4. **Identify the Atomic Number**:
- The element with the configuration `4s^2 3d^7` is Manganese (Mn), which has an atomic number of 25.
- In the `+3` oxidation state, Manganese loses 2 electrons from the `4s` subshell and 1 from the `3d` subshell, resulting in `3d^4`.

5. **Check Other Atomic Numbers**:
- **Atomic Number 26 (Iron)**: Configuration is `4s^2 3d^6`. In `+3` state, it becomes `3d^5`.
- **Atomic Number 22 (Titanium)**: Configuration is `4s^2 3d^2`. In `+3` state, it becomes `3d^1`.
- **Atomic Number 19 (Potassium)**: Configuration is `4s^1`. In `+3` state, it has no `3d` electrons.

6. **Conclusion**:
- The atomic numbers that do not correspond to an element with a `3d^4` configuration in the `+3` oxidation state are 26 (Iron), 22 (Titanium), and 19 (Potassium).

### Final Answer:
The atomic number of the transition element X is not 26, 22, or 19.