Which of the following process refers to ionisation potential ?

Options

A. `X(s) to X^(+) (g) +e^(-)`
B. `X(g) +aq to X^(+) (aq)+e^(-)`
C. `X(g) to X^(+) (g) +e^(-)`
D. `X(g) +e^(-) to X^(-) (g)`

Explanation

To solve the question "Which of the following process refers to ionisation potential?", we need to understand the concept of ionisation potential first. Here’s a step-by-step breakdown:

### Step 1: Understand Ionisation Potential
Ionisation potential (or ionisation energy) is defined as the amount of energy required to remove an electron from the outermost shell of a neutral atom in the gaseous state.

### Step 2: Identify the Process
The process can be represented as follows:
- Consider an atom represented as \( X \) in the gaseous state.
- When we remove one electron from this atom, it transforms into a positively charged ion (cation), represented as \( X^+ \).
- This can be shown in the equation:
\[ X(g) \rightarrow X^+(g) + e^- \]
Here, \( e^- \) represents the electron that has been removed.

### Step 3: Analyze the Options
Now, we need to analyze the provided options to determine which one corresponds to the process of ionisation potential:
- **Option A**: Involves a solid state (not applicable).
- **Option B**: Involves an aqueous state (not applicable).
- **Option C**: Represents the removal of an electron from a gaseous atom (this matches our definition).
- **Option D**: Involves adding an electron (not applicable).

### Step 4: Conclusion
Based on the analysis, the correct option that refers to ionisation potential is **Option C**, as it correctly describes the process of removing an electron from a gaseous atom.