The range of radius ratio (cationic to anionic) for an octahedral arrangement of ions in an ionic solid is

Options

A. `0.155-0.225`
B. `0.225-0.414`
C. `0.414-0.732`
D. `0.732-1.000`

Answer

To determine the range of the radius ratio (cationic to anionic) for an octahedral arrangement of ions in an ionic solid, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Radius Ratio Rule**:
The radius ratio rule relates the size of cations (positively charged ions) to anions (negatively charged ions) in an ionic solid. It is defined as the ratio of the radius of the cation (R⁺) to the radius of the anion (R⁻). This can be expressed as:
\[ \text{Radius Ratio} = \frac{R^+}{R^-} \]

2. **Identify the Range for Octahedral Coordination**:
For an octahedral arrangement of ions, the radius ratio has specific limits. The critical values for the radius ratio that define the stability of the octahedral voids are:
- The lower limit is approximately 0.414.
- The upper limit is approximately 0.732.

3. **Establish the Range**:
Therefore, the range of the radius ratio for an octahedral arrangement can be expressed as:
\[ 0.414 < \frac{R^+}{R^-} < 0.732 \]

4. **Conclusion**:
Based on the above analysis, the range of the radius ratio (cationic to anionic) for an octahedral arrangement in an ionic solid is from 0.414 to 0.732.

### Final Answer:
The range of radius ratio (cationic to anionic) for an octahedral arrangement of ions in an ionic solid is \(0.414\) to \(0.732\).

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