Question

How many effective $N{a}^{+}$ and $C{l}^{-}$ ions are present respectively, in a unit cell of $NaCl$ solid if all ions along the line connecting opposite face centers are absent?

• A. $3,3$
• B. $\frac{7}{2},4$
• C. $\frac{7}{2},\frac{7}{2}$
• D. $4,\frac{7}{2}$

Answer 1

Answer: (A)

$3,3$

In a unit cell of NaCl solid, total $4$ ions each of $N{a}^{+}$ and $C{l}^{-}$ are present.
Here, all ions along the line connecting the opposite face-centers are absent and so, the remaining ions are $3$ $N{a}^{+}$ and $3$ $C{l}^{-}$.