Which material is a hard, brittle, and typically transparent amorphous solid formed by rapidly cooling a fusion of sand, soda and lime?

• A. Metal
• B. Plastic
• C. Cement
• D. Glass

Answer: (D)

Hard, brittle, and transparent amorphous solids form when a molten mixture of silica with additives is cooled rapidly enough to prevent crystal formation. This rapid cooling locks the structure into a disordered, glassy state rather than a regular crystal lattice, which is why the material is both transparent and brittle. The specific combination of sand (silica) with soda and lime is the classic recipe for soda-lime glass, the common glass used for windows and bottles. Its properties arise from the disordered network of bonds that still holds the material together, giving hardness and transparency but little ability to deform without cracking. Metals, cement, and plastics have different internal structures and formation processes, so they do not match the description of a rapidly cooled fusion of sand, soda, and lime.