Which one of the following statements about positive ions is incorrect?

Options

A. They are also known as cations.
B. They are formed when electrons are removed from atoms.
C. They are larger than the atom from which they were formed.
D. They are smaller than the atom from which they were formed.

Explanation

To determine which statement about positive ions (cations) is incorrect, we will analyze the characteristics and formation of positive ions.

### Step-by-Step Solution:

1. **Understanding Positive Ions**:
- Positive ions, also known as cations, are formed when an atom loses one or more electrons.

2. **Formation of Positive Ions**:
- When an atom (let's call it A) is neutral, it has an equal number of protons and electrons.
- When it loses an electron, it becomes positively charged (A+), meaning it now has more protons than electrons.

3. **Characteristics of Cations**:
- Cations are formed by the removal of electrons from neutral atoms.
- Due to the loss of electrons, the effective nuclear charge (the net positive charge experienced by electrons) increases, which pulls the remaining electrons closer to the nucleus.

4. **Comparing Sizes**:
- When we compare the size of the cation (A+) to the neutral atom (A), the cation is actually smaller than the original atom.
- This is because the loss of electrons reduces electron-electron repulsion and allows the nucleus to exert a stronger pull on the remaining electrons.

5. **Evaluating the Statements**:
- **Statement A**: "They are also known as cation." - This is correct.
- **Statement B**: "They are formed when electrons are removed from atoms." - This is correct.
- **Statement C**: "They are larger than the atom from which they were formed." - This is incorrect because cations are smaller than their parent atoms.
- **Statement D**: "They are smaller than the atom from which they were formed." - This is correct.

6. **Conclusion**:
- The incorrect statement about positive ions is **Statement C**: "They are larger than the atom from which they were formed."

### Final Answer:
The incorrect statement about positive ions is **C**: "They are larger than the atom from which they were formed."

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