Question

All the faces of an octahedron can be collectively symbolized by:

• A. 111
• B. [111]
• C. (111)
• D. \{111\}

Hint:

Use parentheses $(hkl)$ for single plane, square brackets $[uvw]$ for directions, and curly braces $\{hkl\}$ for families of planes.

Answer 1

The Correct Option is D

Step 1: Crystallographic notation.
- $(hkl)$ denotes a specific plane. - $[uvw]$ denotes a specific direction. - $\{hkl\}$ denotes a family of symmetry-equivalent planes.

Step 2: Octahedral faces.
An octahedron in cubic crystals is bounded by 8 equivalent $\{111\}$ planes.

Step 3: Conclusion.
Therefore, all faces of an octahedron are represented by the family $\{111\}$.

Final Answer:
\[ \boxed{\{111\}} \]