Question

If the radius of $N{a}^{+}$ ion is $95$ pm and that of $C{l}^{-}$ ion is $181$ pm, then :

• A. co-ordination number of $N{a}^{+}$ is $6$
• B. co-ordination number of $C{l}^{-}$ is $8$
• C. length of the unit cell is $552$ pm
• D. length of the unit cell is $380$ pm

Answer 1

Answer: (A), (C)

co-ordination number of $N{a}^{+}$ is $6$
length of the unit cell is $552$ pm

As in NaCl, limit radius ratio is $\frac{r}{R}=\frac{95}{181}=0.52$ and so, its coordination of cation is $6$ and edge length is $2r+2R=2\times 95+2\times 181=552$ pm.