Which of the following process refers to `IE_(2)` ?

Options

A. `X_((g)) rarr X_((g))^(2+)`
B. `X_((g))^(o+) rarr X_((g))^(2-)`
C. `X_((aq))^(o+) rarr X_((g))^(2+)`
D. `X_((g)) rarr X_((g))^(o+)`

Answer

To determine which process refers to \( IE_2 \) (the second ionization energy), we need to understand the definitions of ionization energy and the specific processes involved.

### Step-by-Step Solution:

1. **Understanding Ionization Energy**:
- Ionization energy (IE) is the energy required to remove an electron from an atom or ion in the gas phase.
- The first ionization energy (\( IE_1 \)) is the energy required to remove the first electron from a neutral gaseous atom.

2. **Defining \( IE_2 \)**:
- The second ionization energy (\( IE_2 \)) is the energy required to remove a second electron from an already positively charged ion (a cation).
- Specifically, \( IE_2 \) refers to the process where a unipositive cation loses an electron to become a dipositive cation.

3. **Writing the Chemical Equation for \( IE_2 \)**:
- If we denote a neutral atom as \( X \), the first ionization process can be represented as:
\[ X(g) \rightarrow X^+(g) + e^- \]
- The second ionization process, which corresponds to \( IE_2 \), can be represented as:
\[ X^+(g) \rightarrow X^{2+}(g) + e^- \]

4. **Identifying the Correct Option**:
- We need to identify which option corresponds to the process of removing an electron from \( X^+ \) to form \( X^{2+} \).
- Based on the definitions, the correct option will involve a gaseous unipositive cation losing an electron.

5. **Conclusion**:
- After analyzing the options provided, the correct answer that describes \( IE_2 \) is the process where a gaseous unipositive cation loses an electron to form a dipositive cation. This matches with option B.

### Final Answer:
The process that refers to \( IE_2 \) is:
\[ X^+(g) \rightarrow X^{2+}(g) + e^- \]
Thus, the correct option is **B**.

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