Question

The number of atoms present in a unit cell of a monoatomic substance (element) of a simple cubic lattice, body-centred cubic and face centred cubic, respectively, are___________.

• A. $8,8$ and $14$
• B. $1,2$ and $4$
• C. $4,5$ and $6$
• D. $2,3$ and $5$

Answer 1

Answer: (B)

$1,2$ and $4$

Limiting radius ratio $=r/R$	Coordination Number of cation	Structural Arrangement (Geometry of voids )	Example
$0.155-0.225$	$3$	Plane Trigonal	Boron Oxide
$0.225-0.414$	$4$	Tetrahedral	$ZnS,Si{O}_2$
$0.414-0.732$	$4$	Square planar	$-$
$0.414-0.732$	$6$	Octahedral	$NaCl,Mg{O}_2$
$0.732-1.000$	$8$	Cubic	$CsCl$