Question

In $CaF_2$ type (fluorite structure) $Ca^{2+}$ ions form $(A)$ structure and $F^-$ ions are present in all $(B)$ voids. The coordination number of $Ca^{2+}$ is $(C)$ and $F^-$ is $(D)$.
$(A)$, $(B)$, $(C)$ and $(D)$ respectively are

	$A$	$B$	$C$	$D$
(a)$\,\,$	$ccp\,\,$	octahedral$\,$	$8\,\,$	$4\,\,$
(b)$\,\,$	$bcc\,\,$	tetrahedral$\,\,$	$4\,\,$	$8\,\,$
(c)$\,\,$	$ccp\,\,$	tetrahedral$\,\,$	$8\,\,$	$4\,\,$
(d)$\,\,$	$ccp$	octahedral$\,\,$	$4$	$8\,\,$

• A. a
• B. b
• C. c
• D. d

Answer 1

Answer: (C)

$Ca^{2+}$ ions form $ccp$ structure while $F^-$ ions are in all tetrahedral holes and coordination numbers are $8$ and $4$.