Which of the following statements are correct?

Options

A. The coordination number of each type of ion in CsCl crystal is 8
B. A metal that crystallizes in bcc structure has coordination number 12.
C. A unit cell of an ionic crystal shares some of its ions with other unit cells.
D. The length of the unit cell in NaCl is 552 pm
`(r_(Na^(+)) = 95 " pm" , r_(Cl^(-)) = 181 " pm ")`.

Explanation

To determine which statements are correct regarding the solid state, let's analyze each statement step by step.

### Step 1: Analyze the first statement about CSCl
- **Statement**: The coordination number of each type of ion in CSCl is 8.
- **Explanation**: CSCl (Cesium Chloride) crystallizes in a body-centered cubic (BCC) lattice structure. In a BCC lattice, each ion is surrounded by 8 other ions. Therefore, the coordination number for both Cs+ and Cl- in CSCl is indeed 8.
- **Conclusion**: This statement is **correct**.

### Step 2: Analyze the second statement about BCC structure
- **Statement**: A metal that crystallizes in BCC structure has a coordination number of 12.
- **Explanation**: In a BCC structure, the coordination number is 8, not 12. Coordination number 12 is characteristic of face-centered cubic (FCC) structures. Therefore, this statement is incorrect.
- **Conclusion**: This statement is **incorrect**.

### Step 3: Analyze the third statement about ionic crystals
- **Statement**: A unit cell of an ionic crystal shares some of its ions with other unit cells.
- **Explanation**: In ionic crystals, the unit cell does indeed share some of its ions with adjacent unit cells. For example, the ions at the corners of the unit cell are shared among multiple unit cells. This sharing is a fundamental characteristic of how ionic crystals are structured.
- **Conclusion**: This statement is **correct**.

### Step 4: Analyze the fourth statement about NaCl
- **Statement**: The length of the unit cell of NaCl is given as 552 picometers, with the radius of Na+ being 95 picometers and Cl- being 181 picometers.
- **Explanation**: The edge length of the NaCl unit cell can be calculated by adding the radius of the cation (Na+) and the radius of the anion (Cl-), and then doubling that sum (since the unit cell contains one of each ion).
- Calculation:
- Radius of Na+ = 95 pm
- Radius of Cl- = 181 pm
- Total radius = 95 pm + 181 pm = 276 pm
- Edge length = 2 × 276 pm = 552 pm
- **Conclusion**: This statement is **correct**.

### Final Summary of Statements
1. **CSCl coordination number is 8** - **Correct**
2. **BCC structure has coordination number 12** - **Incorrect**
3. **Ionic crystal unit cell shares ions with other unit cells** - **Correct**
4. **NaCl unit cell length is 552 pm** - **Correct**