Which of the following structures is not correctly matched ?

Options

A. NaCl type - `Cl^-` ions in ccp structure. `Na^+` ions in half octahedral holes
B. ZnS type - `S^(2-)` ions in ccp structure . `Zn^(2+)` ions in alternate tetrahedral voids .
C. `CaF_2` type - `Ca^(2+)` ions in ccp structure `F^-` ions in all tetrahedral voids
D. `Na_2O` type - `O^(2-)` ions in ccp structure. `Na^(+)` ions in all tetrahedral holes .

Explanation

To solve the question of which structure is not correctly matched, we will analyze each of the given options one by one.

### Step-by-Step Solution:

1. **Analyze the First Option:**
- The first option states that in sodium chloride (NaCl) type, chloride ions are in a close-packed (CPP) structure and sodium ions are in half octahedral holes.
- **Correct Information:** In NaCl, chloride ions are actually arranged in a face-centered cubic (FCC) structure, and sodium ions occupy half of the octahedral holes.
- **Conclusion:** This option is incorrectly matched.

2. **Analyze the Second Option:**
- The second option mentions that in zinc sulfide (ZnS) type, zinc sulfide is a zinc blende structure.
- **Correct Information:** In ZnS, the sulfide ions are in a cubic close-packed (CCP) structure, and zinc ions occupy alternate tetrahedral voids.
- **Conclusion:** This option is correctly matched.

3. **Analyze the Third Option:**
- The third option states that in calcium fluoride (CaF2), calcium fluoride is a fluoride type structure.
- **Correct Information:** In CaF2, calcium ions are arranged in a CCP structure, and fluoride ions occupy all the tetrahedral voids.
- **Conclusion:** This option is correctly matched.

4. **Analyze the Fourth Option:**
- The fourth option indicates that in sodium oxide (Na2O) type, sodium oxide is an anti-fluoride structure.
- **Correct Information:** In Na2O, oxide ions are arranged in a CCP structure, and sodium ions occupy all the tetrahedral holes.
- **Conclusion:** This option is correctly matched.

### Final Conclusion:
After analyzing all the options, we find that the first option is the only one that is not correctly matched. Therefore, the answer to the question is:

**The first option is not correctly matched.**

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