Which of the following transitions do represents first ionisation potential ?

Options

A. `M_((g))^(-) rarr M_((g))`
B. `M_((g)) rarr M_((g))^(+)`
C. `M_((g))^(+) rarr M_((g))^(2+)`
D. `M_((g))^(+2) rarr M_((g))^(3+)`

Answer

To determine which transition represents the first ionization potential, we need to understand the concept of ionization potential and how it is represented in chemical equations.

### Step-by-Step Solution:

1. **Understanding Ionization Potential**:
- The first ionization potential (IP) refers to the energy required to remove the most loosely bound electron from a neutral atom in its ground state, resulting in a positively charged ion.

2. **Identifying the Transition**:
- The transition for the first ionization potential can be represented as:
\[ \text{M (g)} \rightarrow \text{M}^+ (g) + e^- \]
- Here, M represents a neutral atom in the gaseous state. When it loses one electron, it becomes a cation (M⁺).

3. **Analyzing Options**:
- We need to look at the given options and identify which one matches the above transition.
- The correct representation of the first ionization potential will show a neutral atom converting to a cation with the release of an electron.

4. **Conclusion**:
- After analyzing the options, we find that option B represents the correct transition for the first ionization potential:
\[ \text{M (g)} \rightarrow \text{M}^+ (g) + e^- \]

### Final Answer:
- The transition that represents the first ionization potential is option B.

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