Question

Select the correct statements among following:
$(a=$ edge length of unit cell).

• A. Nearest neighbour distance in $NaCl=\frac{a}{2}$
• B. Nearest neighbour distance in $Ca{F}_2=\frac{a\sqrt{3}}{4}$
• C. Nearest neighbour distance in $N{a}_{2}O=\frac{a\sqrt{3}}{4}$
• D. Nearest neighbour distance in $CsCl=\frac{a\sqrt{3}}{2}$

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A Nearest neighbour distance in $NaCl=\frac{a}{2}$
B Nearest neighbour distance in $Ca{F}_2=\frac{a\sqrt{3}}{4}$
C Nearest neighbour distance in $N{a}_{2}O=\frac{a\sqrt{3}}{4}$
D Nearest neighbour distance in $CsCl=\frac{a\sqrt{3}}{2}$

(A) Nearest neighbour distance in $NaCl=\frac{a}{2}$

$Na+$ at edge center and $C{l}^{-}$ at body corner or face center.

(B) $C{a}^{2+}$ at body corner and $F^{-}$ at tetrahedral void

Nearest distance= $\frac{a\sqrt{3}}{4}$

(C) $N{a}^{+}$ at tetrahedral void and $O^{2-}$ at body corner

Nearest distance= $\frac{a\sqrt{3}}{4}$

(D) $C{s}^{+}$ at body center and $C{l}^{-}$ at body corner

Nearest distance= $\frac{a\sqrt{3}}{2}$