A large difference between the fourth and fifth ionization energies indicates the presence of:

Options

A. 5 valence electrons in an atom
B. 6 valence electrons in an atom
C. 4 valence electrons in an atom
D. 8 valence electrons in an atom

Answer

To solve the question regarding the large difference between the fourth and fifth ionization energies, we will analyze the implications of such a difference in terms of electron configuration and valence electrons.

### Step-by-Step Solution:

1. **Understanding Ionization Energy**:
- Ionization energy is the energy required to remove an electron from an atom or ion. The first ionization energy (IE1) is the energy needed to remove the first electron, the second ionization energy (IE2) is for the second electron, and so on.

2. **Identifying the Context of the Question**:
- The question states that there is a large difference between the fourth (IE4) and fifth (IE5) ionization energies. This indicates a significant increase in energy required to remove the fifth electron compared to the fourth.

3. **Analyzing the Implication of Large Differences**:
- A large jump in ionization energy suggests that the fifth electron is being removed from a much more stable electron configuration. This typically occurs when the atom has achieved a noble gas configuration or a filled subshell after the removal of the first four electrons.

4. **Determining the Number of Valence Electrons**:
- If removing the first four electrons requires a relatively low amount of energy, but removing the fifth electron requires a significantly higher amount of energy, it indicates that the atom originally had four valence electrons.
- This is because after removing four electrons, the atom is likely reaching a stable electron configuration, making it much harder to remove the fifth electron.

5. **Conclusion**:
- Therefore, the presence of a large difference between the fourth and fifth ionization energies indicates that the atom has **4 valence electrons**.

### Final Answer:
The presence of a large difference between the fourth and fifth ionization energies indicates the presence of **4 valence electrons**.

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