I.When a gase phase atom in its ground state gains an electron the enthalpy change is called electron gain enthalpy
II.The electron gain process is always exothermic
III.The ionisation enthalpy process is always endothermic choose the correct option

Options

A. I and II are correct
B. all are correct
C. I and III are correct while II is incorrect
D. All of the above

Answer

To solve the question, we need to evaluate the three statements provided regarding electron gain enthalpy and ionization enthalpy. Let's analyze each statement step by step.

### Step 1: Analyze Statement I
**Statement I:** "When a gaseous phase atom in its ground state gains an electron, the enthalpy change is called electron gain enthalpy."

- This statement is **correct**. When an atom in its gaseous phase and ground state gains an electron, the energy change associated with this process is indeed referred to as the electron gain enthalpy. It is typically represented as a negative value because energy is released when an electron is added to a neutral atom.

### Step 2: Analyze Statement II
**Statement II:** "The electron gain process is always exothermic."

- This statement is **incorrect**. While many elements, especially non-metals like halogens, release energy when they gain an electron (making the process exothermic), there are exceptions. For example, noble gases and certain elements with half-filled or fully filled orbitals do not favor the addition of an electron due to their stable electronic configurations. In these cases, energy must be supplied to add an electron, making the process endothermic.

### Step 3: Analyze Statement III
**Statement III:** "The ionization enthalpy process is always endothermic."

- This statement is **correct**. Ionization enthalpy refers to the energy required to remove an electron from an atom or ion. This process always requires energy input, as overcoming the attraction between the negatively charged electron and the positively charged nucleus necessitates energy. Therefore, ionization enthalpy is always a positive (endothermic) value.

### Conclusion
Based on the analysis:
- **Statement I** is correct.
- **Statement II** is incorrect.
- **Statement III** is correct.

Thus, the correct options are **I and III**.

### Final Answer
The correct option is: **I and III are correct; II is incorrect.**

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