Question

If the radius of $C{s}^{\oplus }=1.69\mathring{A}$ and $B{r}^{⊝}=1.69\mathring{A}$, then which of the following is/are correct?

• A. The edge length of unit cell is $4.2\mathring{A}$.
• B. The coordination number for $C{s}^{+}$ is $6$.
• C. CsBr has bcc-type structure.
• D. $B{r}^{-}$ ions touch each other along the edge.

Answer 1

Answer: (A), (C)

The correct options are
A The edge length of unit cell is $4.2\mathring{A}$.
C CsBr has bcc-type structure.

$\frac{r_{+}}{r_{-}}=1$, therefore $CsBr$ has bcc type structure.
In BCC type structure, $4r=a\sqrt{3}$
$a=4.2\mathring{A}$