Alloys as homogeneous metal mixtures

Steps:

• Recall that an alloy is a homogeneous solid solution of two or more metals with atoms randomly distributed in a crystal lattice.
• Examine each diagram for irregular placement of different atoms within a single lattice structure.
• Eliminate options showing uniform atoms (pure metal), ordered alternating atoms (compound), or distinct separate phases (heterogeneous mixture).
• Identify the diagram with mixed atoms interspersed randomly as the alloy representation.

Why D is correct:

• D depicts a substitutional alloy where different metal atoms substitute randomly in the lattice sites, matching the definition of a homogeneous solid solution.

Why the others are wrong:

• A shows a regular lattice of identical atoms, representing a pure metal.
• B illustrates ordered alternating atoms, indicating an intermetallic compound.
• C displays separate clusters of different atoms, signifying a heterogeneous mechanical mixture.

Final answer: D