Which one of the following statements is wrong about zinc blende type structure ?

Options

A. Each `Zn^(2+)` ion is surrounded tetrahedrally by four `S^(2-)` ions and each `S^(2-)` ion by four `Zn^(2+)` ions
B. `S^(2-)` ions form fcc arrangement
C. AgBr has zinc blende type structure
D. Cuprous halides have zinc blende type structure

Answer

To determine which statement is wrong about the zinc blende type structure, we need to analyze the properties and characteristics of zinc sulfide (ZnS), which adopts the zinc blende structure.

### Step-by-Step Solution:

1. **Understanding the Zinc Blende Structure**:
- Zinc blende, or zinc sulfide (ZnS), has a face-centered cubic (FCC) arrangement of sulfide ions (S²⁻) and zinc ions (Zn²⁺) occupying tetrahedral voids.

2. **Coordination Number**:
- In the zinc blende structure, each zinc ion (Zn²⁺) is surrounded tetrahedrally by four sulfide ions (S²⁻). Conversely, each sulfide ion is surrounded by four zinc ions. Thus, the coordination number for both ions is 4.

3. **Analyzing the Statements**:
- **Option 1**: "Each Zn²⁺ ion is surrounded tetrahedrally by 4 S²⁻ ions and each S²⁻ ion by 4 Zn²⁺ ions."
- This statement is correct based on our understanding of the structure.

- **Option 2**: "Sulfide ions form FCC arrangement."
- This statement is also correct, as the sulfide ions indeed form an FCC lattice.

- **Option 3**: "AgBr has zinc blende type structure."
- This statement is incorrect. AgBr (silver bromide) adopts a sodium chloride (NaCl) type structure, not a zinc blende structure.

- **Option 4**: "Cuprous halides have zinc blende type structure."
- This statement is correct, as cuprous halides (like CuCl) can exhibit a zinc blende structure.

4. **Conclusion**:
- The wrong statement about zinc blende type structure is **Option 3**, which incorrectly identifies AgBr as having a zinc blende type structure.

### Final Answer:
The wrong statement about zinc blende type structure is **Option 3**: "AgBr has zinc blende type structure."

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