Question

A crystalline solid of the type AB\(_2\) has a ccp arrangement for its element B. So, A occupies: 
 

• A. 66% of tetrahedral voids
• B. 33% of tetrahedral voids
• C. 33% of octahedral voids
• D. 66% of octahedral voids

Hint:

For ionic or interstitial compounds, understanding the occupancy of tetrahedral and octahedral voids helps in determining the structure and stoichiometry of the compound.

Answer 1

The Correct Option is C

In a close-packed cubic arrangement (ccp or fcc), the number of octahedral voids is equal to the number of atoms forming the lattice, while the number of tetrahedral voids is twice that number.
For a compound of type AB₂:
- The B atoms (which form the close-packed structure) contribute octahedral voids.
- The A atoms occupy some of these voids.
- Since the formula suggests a 1:2 ratio of A to B, A atoms occupy ¹/₃ (or 33%) of the octahedral voids.
Thus, the correct answer is that A occupies 33% of the octahedral voids.