For an ionic crystal of the formula `AX` and cooradition number `6`, the value of radius ratio will be

Options

A. greater than `0.73`
B. between `0.73` and `0.41`
C. between `0.41` and `0.22`
D. less than `0.22`

Explanation

To determine the radius ratio for an ionic crystal of the formula AX with a coordination number of 6, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Radius Ratio**:
The radius ratio is defined as the ratio of the radius of the cation (r+) to the radius of the anion (r-). This is expressed mathematically as:
\[ \text{Radius Ratio} = \frac{r^+}{r^-} \]

2. **Identifying Coordination Number**:
The coordination number indicates how many nearest neighbor ions surround a central ion. In this case, the coordination number is given as 6.

3. **Using Radius Ratio Table**:
There is a known relationship between the coordination number and the radius ratio. For a coordination number of 6, the radius ratio falls within a specific range. According to standard tables:
- For coordination number 6, the radius ratio lies between 0.414 and 0.732.

4. **Conclusion**:
Therefore, for an ionic crystal of the formula AX with a coordination number of 6, the radius ratio will be:
\[ 0.414 < \text{Radius Ratio} < 0.732 \]

5. **Selecting the Correct Option**:
If options are provided, the correct option would be the one that states that the radius ratio lies between 0.414 and 0.732.

### Final Answer:
The value of the radius ratio for an ionic crystal of the formula AX with a coordination number of 6 is between 0.414 and 0.732.

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