The ionization energy will be maximum for the process.

Options

A. ` Ba to Ba^(+)`
B. `Be to Be^(+)`
C. `Cs to CS^(+)`
D. `Li to Li^(+)`

Answer

To determine which element has the maximum ionization energy, we need to analyze the ionization energies of the given elements: barium (Ba), beryllium (Be), cesium (Cs), and lithium (Li).

### Step-by-Step Solution:

1. **Understanding Ionization Energy**:
Ionization energy is the energy required to remove an electron from an atom in its gaseous state. Generally, the higher the ionization energy, the more energy is needed to remove an electron.

2. **Identify the Electronic Configurations**:
- **Barium (Ba)**: [Xe] 6s²
- **Beryllium (Be)**: [He] 2s²
- **Cesium (Cs)**: [Xe] 6s¹
- **Lithium (Li)**: [He] 2s¹

3. **Trends in Ionization Energy**:
- Ionization energy generally increases across a period (from left to right) and decreases down a group (from top to bottom) in the periodic table.
- Beryllium, being in the second period, has a higher ionization energy compared to barium, which is in the sixth period.
- Barium has a lower ionization energy due to its larger atomic size and the presence of more electron shells, which results in increased electron shielding.

4. **Comparison of Elements**:
- **Beryllium (Be)**: Has a full outer shell (2s²), making it more stable and requiring more energy to remove an electron.
- **Barium (Ba)**: Has a partially filled outer shell (6s²), but due to its larger size, it has lower ionization energy than beryllium.
- **Cesium (Cs)**: Has a single electron in the outermost shell (6s¹), making it very easy to remove, thus it has a low ionization energy.
- **Lithium (Li)**: Has a single electron in the outermost shell (2s¹), but being in a higher period than beryllium, it has lower ionization energy than beryllium.

5. **Conclusion**:
Among the elements analyzed, **beryllium (Be)** has the highest ionization energy due to its stable electronic configuration and position in the periodic table.

### Final Answer:
The ionization energy will be maximum for **beryllium (Be)**.