Question

In the closest packing of atoms $A(\text{radius}:r_a)$, the radius of atom $B$ that can be fitted into tetrahedral void is:

• A. $0.155r_a$
• B. $0.732r_a$
• C. $0.225r_a$
• D. $0.414r_a$

Answer 1

The correct option is C $0.225r_a$

Limiting radius ratio of tetrahedral void,
$\frac{r_c}{r_a}=0.225$
$\Rightarrow r_c=0.0225r_a$
Where ,
$r_c=r_{cation}\text{and}{r}_a=r_{anion}$.