Statement-1:For NaCl structure, `Cl^-` ions occupy corners and face centre and `Na^+` ions occupy edge centres and body centre.
Statement-2:The radius ratio of NaCl structure varies from 0.414 to 0.732

Options

A. Statement-1 is true, statement-2 is true, statement-2 is a correct explanation for statement-1
B. Statement-1 is true, statement-2 is true, statement-2 is not correct explanation for statement-1
C. Statement-1 is true, statement-2 is false
D. Statement-1 is false, statement-2 is true

Answer

To solve the question, we need to analyze both statements regarding the NaCl structure and the radius ratio.

### Step-by-Step Solution:

**Step 1: Analyze Statement 1**
- Statement 1 claims that in the NaCl structure, Cl⁻ ions occupy the corners and face centers, while Na⁺ ions occupy the edge centers and body center.
- In the NaCl crystal structure, Cl⁻ ions indeed form a face-centered cubic (FCC) lattice. In an FCC lattice:
- There are 8 corner atoms, each contributing \( \frac{1}{8} \) to the unit cell, and 6 face-centered atoms, each contributing \( \frac{1}{2} \).
- Total contribution from Cl⁻ ions:
\[ 8 \times \frac{1}{8} + 6 \times \frac{1}{2} = 1 + 3 = 4 \]
- Na⁺ ions occupy the octahedral voids created by the Cl⁻ ions, which are located at the edge centers and one at the body center.
- Therefore, Statement 1 is **true**.

**Step 2: Analyze Statement 2**
- Statement 2 states that the radius ratio of the NaCl structure varies from 0.414 to 0.732.
- The radius ratio (r/R) for octahedral voids is defined as the ratio of the radius of the cation (Na⁺) to the radius of the anion (Cl⁻).
- For NaCl, the radius ratio indeed falls within the range of 0.414 to 0.732, which is characteristic for octahedral coordination.
- Therefore, Statement 2 is also **true**.

**Step 3: Determine the Relationship Between the Statements**
- Since both statements are true, we need to assess if Statement 2 provides a correct explanation for Statement 1.
- Statement 2 explains the conditions under which Na⁺ ions can occupy the octahedral voids formed by Cl⁻ ions, thus supporting the description in Statement 1.
- Therefore, Statement 2 is a correct explanation for Statement 1.

### Conclusion:
Both statements are true, and Statement 2 correctly explains Statement 1.

**Final Answer: Option 1 (Statement 1 is true, Statement 2 is true, and Statement 2 is a correct explanation for Statement 1).**

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