Step 1: Understanding the Concept:
Isotropy refers to the property of a material where its physical properties (like electrical conductivity, refractive index, thermal expansion) are the same in all directions. This is a characteristic feature of amorphous solids. Conversely, anisotropy means properties vary with direction, which is typical of crystalline solids due to their highly ordered arrangement of particles.
Step 2: Key Formula or Approach:
Identify whether each given solid is crystalline or amorphous. The amorphous solid will be the isotropic one.
Step 3: Detailed Explanation:
Let's classify the given solids:
- (A) Glass is an amorphous solid (a supercooled liquid). Since its internal structure is random and lacks long-range order, its properties are uniform in all directions. Therefore, it is isotropic.
- (B) Ceramics are generally crystalline or partially crystalline materials. Crystalline regions cause anisotropy.
- (C) Graphite is a covalent network solid with a distinct layered crystalline structure. It is highly anisotropic (e.g., conducts electricity parallel to layers but not perpendicular to them).
- (D) Ice is a crystalline solid formed by a network of hydrogen bonds. Thus, it is anisotropic.
Step 4: Final Answer:
Glass is the only clear example of an isotropic amorphous solid among the choices.