Question

Statement 1 : If the length of the unit cell of $LiCl$ having $NaCl$ structure is $5.14\, \mathring{A}$, the ionic radius of $Cl^-$ ion is $1.82 \,\mathring{A}$.
Statement 2 : Anion-anion contact is retained in $LiCl$ structure because anions constitute the lattice.

• A. If both Statement $1$ and Statement $2$ are true and the statement $2$ is the correct explanation of the statement $1$
• B. If both Statement $1$ and Statement $2$ are true but statement $2$ is not the correct explanation of the statement $1$
• C. If Statement $1$ is true but Statement $2$ is false
• D. If Statement $1$ is false but Statement $2$ is true

Answer 1

Answer: (A)

If anion-anion contact is retained, then as shown in the adjoining figure.

Interionic distance of $LiCl = a/2$
$ = 5.14 \mathring{A}/2 = 2.57 \mathring{A}$
$BC = \sqrt{AB^2 + AC^2}$
$ = \sqrt{(2.57)^2+(2.57)^2} $
$= 3.63 \mathring{A}$
Radius of $Cl^-$ ion $ = \frac{1}{2} BC$
$ = \frac{1}{2} \times 3.63 = 1.81\,\mathring{A}$
Hence, statement $2$ is the correct explanation of statement $1$.