The radius ratio of KF is 0.98. The structure of KF is of the type

Options

A. NaCl
B. ZnS
C. CsCl
D. Graphite

Answer

To determine the structure of KF based on its radius ratio, we can follow these steps:

### Step 1: Understand Radius Ratio
The radius ratio (r+) is defined as the ratio of the radius of the cation (r+) to the radius of the anion (r-). For KF, the radius ratio is given as 0.98.

### Step 2: Identify Coordination Number Ranges
The coordination number (CN) is the number of nearest neighbors surrounding a central atom in a crystal structure. The radius ratio helps us determine the coordination number:
- **0.155 to 0.225**: CN = 3
- **0.225 to 0.414**: CN = 4
- **0.414 to 0.732**: CN = 6
- **0.732 to 1**: CN = 8

### Step 3: Analyze the Given Radius Ratio
Since the radius ratio of KF is 0.98, we can see that it falls into the range of 0.732 to 1. This indicates that the coordination number for KF is 8.

### Step 4: Identify the Structure Type
The structure type that corresponds to a coordination number of 8 is similar to that of cesium chloride (CsCl). In CsCl, each cation is surrounded by 8 anions and vice versa, forming a cubic lattice.

### Step 5: Conclusion
Based on the analysis, the structure of KF is of the type CsCl.

### Final Answer
The structure of KF is of the type **c. Caesium chloride**.

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