Question

In chromium chloride $\left(C r C l_{3}\right), \, Cl^{-}$ ions have cubic close packed arrangement and $Cr^{3 +}$ ions are present in the octahedral holes. The fraction of the total number of holes occupied is

• A. $\frac{1}{3}$
• B. $\frac{1}{6}$
• C. $\frac{1}{9}$
• D. $\frac{1}{12}$

Answer 1

Answer: (C)

In $CrCl_{3}$ for every, $3Cl^{-}$ ions, there is one $Cr^{3 +}$ ion is present.
Thus, if there are $3Cl^{-}$ ions are present in CCP.
Number of octahedral voids = 3, and tetrahedral voids = 6
Total voids = 3+6=9
As $1 \, Cr^{3 +}$ ion is present in the octahedral void, therefore, fraction of holes occupied $=\frac{1}{9}$