In which type of viods magnesium and silicon is present respectively in asbestos `(Mg_(3)Si_(2)O_(5))` if `r_(Mg^(2+))//r_(O^(2)) = 0.59` and `(r_(Si^(4+)))/(r_(O^(2-))) = 0.29`

Options

A. octahedral and tetrahedral
B. Tetrahedral and octahedral
C. both in tetrahedral
D. both in octahedral

Explanation

To determine the type of voids in which magnesium and silicon are present in asbestos (Mg₃Si₂O₅), we will analyze the given radius ratios and apply the radius ratio rule.

### Step-by-Step Solution:

1. **Identify the given radius ratios**:
- For magnesium (Mg²⁺) and oxygen (O²⁻), the radius ratio \( \frac{r_{Mg^{2+}}}{r_{O^{2-}}} = 0.59 \).
- For silicon (Si⁴⁺) and oxygen (O²⁻), the radius ratio \( \frac{r_{Si^{4+}}}{r_{O^{2-}}} = 0.29 \).

2. **Analyze the radius ratio for magnesium**:
- The radius ratio \( 0.59 \) lies between \( 0.414 \) and \( 0.732 \).
- According to the radius ratio rule, this indicates that magnesium occupies **octahedral voids**. In octahedral voids, the coordination number is 6.

3. **Analyze the radius ratio for silicon**:
- The radius ratio \( 0.29 \) lies between \( 0.225 \) and \( 0.414 \).
- This indicates that silicon occupies **tetrahedral voids**. In tetrahedral voids, the coordination number is 4.

4. **Conclusion**:
- Therefore, magnesium is present in octahedral voids, and silicon is present in tetrahedral voids in asbestos.

### Final Answer:
- Magnesium (Mg²⁺) is present in **octahedral voids**.
- Silicon (Si⁴⁺) is present in **tetrahedral voids**.