The energy required to remove an electron from the outermost shell of an isolate gaseous atom is known as `IE_(1)` of that atom. Similarly, the enrgy required for the removal of the electron from the unipositive ion, diapositive ion and tripositive ion are known as `IE_(2),IE_(3)` and `IE_(4)` respectively, and are called successive ionisation energies. The magnitude of the charge depends on the size of the orbital of electron. Electrons in smaller orbitals are on average close with each other and have more repulsion. Thus for `Be(2s^(2))`, the `IE_(1)` and `IE_(2)` are `9.3` and `18.2 eV "atom"^(1)`, whereas for `Ca(4s^(2))`, the values are `6.1` and `11.9 eV`.
Among the following ionisation reactions, which one will have the maximum value of ionisation energy?

Options

A. `Be rarr Be^(o+)`
B. `Be^(o+) rarrBe^(2+)`
C. `Sr rarr Sr^(o+)`
D. `Sr^(o+) rarrSr^(2)`

Explanation

To determine which ionization reaction will have the maximum value of ionization energy, we need to analyze the given information about ionization energies and the elements 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. The first ionization energy (IE₁) refers to removing the first electron from a neutral atom, while the second ionization energy (IE₂) refers to removing an electron from a unipositive ion, and so on.

2. **Given Data**:
- For Beryllium (Be):
- IE₁ = 9.3 eV
- IE₂ = 18.2 eV
- For Calcium (Ca):
- IE₁ = 6.1 eV
- IE₂ = 11.9 eV

3. **Identifying the Reactions**:
- The reactions provided in the question involve the removal of electrons from Beryllium and Strontium:
- Reaction 1: Be → Be⁺ (IE₁)
- Reaction 2: Be⁺ → Be²⁺ (IE₂)
- Reaction 3: Sr → Sr⁺ (IE₁)
- Reaction 4: Sr⁺ → Sr²⁺ (IE₂)

4. **Comparing Ionization Energies**:
- We know that IE₂ is generally greater than IE₁ for any element because removing an electron from a positively charged ion (cation) requires more energy due to the increased effective nuclear charge.
- Therefore, we can eliminate the first ionization energies (IE₁) of both Beryllium and Strontium from consideration.

5. **Evaluating IE₂ Values**:
- For Beryllium:
- IE₂ = 18.2 eV
- For Strontium:
- IE₂ = 11.9 eV

6. **Conclusion**:
- Since 18.2 eV (for Be) is greater than 11.9 eV (for Sr), the maximum value of ionization energy among the given reactions is for the second ionization energy of Beryllium (Be⁺ → Be²⁺).

### Final Answer:
The reaction with the maximum value of ionization energy is: **Be⁺ → Be²⁺ (IE₂)**.

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