Question

What is the type of hole occupied if limiting value of $\dfrac{r^+}{r^-}$ is in the range of $0.225$ to $0.414$ ?

• A. Octahedral
• B. Cubic
• C. Planar triangular
• D. Tetrahedral

Hint:

Radius ratio ranges: Tetrahedral (0.225–0.414), Octahedral (0.414–0.732).

Answer 1

The Correct Option is D

Step 1: Radius ratio rule.
The type of interstitial hole occupied by a cation depends on the radius ratio $\dfrac{r^+}{r^-}$.

Step 2: Given range.
For tetrahedral voids, the radius ratio lies between $0.225$ and $0.414$.

Step 3: Identification of hole type.
Since the given radius ratio falls in this range, the cation occupies a tetrahedral hole.

Step 4: Conclusion.
Therefore, the correct answer is Tetrahedral.