A crystalline solid `XY_(3)` has ccp arrangement for its element Y. The element X occupies :

Options

A. `66%` of tetrahedral holes
B. `33%` of tetrahedral holes
C. `66%` of octahedral holes
D. `33%` of octahedral holes

Explanation

To solve the problem, we need to analyze the crystalline solid XY₃ with a ccp (cubic close-packed) arrangement for the element Y and determine where the element X occupies the voids.

### Step-by-Step Solution:

1. **Understanding the CCP Structure:**
- In a cubic close-packed (ccp) structure, there are 4 atoms per unit cell. This is because there are 8 corner atoms (1/8 each contributes 1 atom) and 6 face-centered atoms (1/2 each contributes 3 atoms), resulting in a total of 4 atoms.

2. **Identifying the Number of Y Atoms:**
- The formula given is XY₃. Since Y occupies the ccp arrangement, we conclude that there are 4 Y atoms in the unit cell.

3. **Calculating the Number of Tetrahedral and Octahedral Voids:**
- In a ccp structure, the number of tetrahedral voids is 8 and the number of octahedral voids is 4.
- Therefore, for 4 Y atoms, we have:
- Tetrahedral voids = 8
- Octahedral voids = 4

4. **Determining the Occupation of Element X:**
- The question asks where the element X occupies. We can check both types of voids (tetrahedral and octahedral) to see which one gives us a valid answer.

5. **Calculating the Occupation in Tetrahedral Voids:**
- If X occupies tetrahedral voids, the number of X atoms would be \( \frac{4}{3} \) (since there are 4 Y atoms and the ratio is 1:3).
- The percentage of tetrahedral voids occupied by X would be:
\[ \text{Percentage} = \left( \frac{\frac{4}{3}}{8} \right) \times 100 = \left( \frac{4}{24} \right) \times 100 = 16.67\% \]
- This percentage does not match any of the options.

6. **Calculating the Occupation in Octahedral Voids:**
- If X occupies octahedral voids, the number of X atoms would again be \( \frac{4}{3} \).
- The percentage of octahedral voids occupied by X would be:
\[ \text{Percentage} = \left( \frac{\frac{4}{3}}{4} \right) \times 100 = \left( \frac{4}{12} \right) \times 100 = 33.33\% \]
- This matches option D (33% of octahedral holes).

7. **Conclusion:**
- Therefore, the element X occupies 33% of the octahedral holes in the ccp arrangement of Y.

### Final Answer:
The element X occupies **33% of octahedral holes**.

---