Which of the following is an example of an amorphous solid?

An amorphous solid is characterized by a lack of long-range order in its molecular arrangement, meaning that its atoms are not organized in a definite pattern. This contrasts with crystalline solids, where atoms are arranged in a highly ordered structure.

Common salt, also known as sodium chloride, is actually a crystalline solid that has a well-defined structural arrangement. On the other hand, options like diamond and quartz are also crystalline solids with well-defined structures, as diamond has a specific arrangement of carbon atoms (in a tetrahedral structure) and quartz has a repeating pattern of silicon and oxygen atoms.

Steel, while it may not be as structured as pure metals, typically exhibits a crystalline structure due to the arrangement of its iron and carbon atoms, especially when alloyed.

The concept of amorphous solids is often represented by materials like glass or certain types of plastics. A common example of an amorphous solid is glass itself, which does not have a long-range order in its atomic structure, leading to its amorphous qualities. In this context, the correct identification of an amorphous solid requires recognizing materials that lack a clear lattice structure, rather than mixing different types of substances that exhibit crystalline properties.