Question

The total number of Na and Cl ions per unit cell of the NaCl crystal is:

• A. 2
• B. 4
• C. 8
• D. 16

Answer 1

The Correct Option is C

In the NaCl crystal structure:

• Each unit cell contains 4 Na⁺ ions and 4 Cl⁻ ions.
• These ions are arranged in a face-centered cubic (FCC) structure.
• Each corner ion is shared by 8 adjacent cells, and each face-centered ion is shared by 2 adjacent cells.

Calculation:

The total number of Na⁺ and Cl⁻ ions per unit cell is:

\[ 4 \, \text{Na}^+ + 4 \, \text{Cl}^- = 8 \, \text{ions} \]

Conclusion:

Therefore, the total number of Na⁺ and Cl⁻ ions per unit cell of the NaCl crystal is:

\[ \boxed{8 \, \text{ions}} \]