What describes a substitutional solid solution?

A substitutional solid solution occurs when the solute atoms replace or occupy positions of the solvent atoms in the crystal lattice of a solid. This typically happens when the solute and solvent metals have similar atomic sizes and similar chemical properties. In such a solution, the overall structure of the material is maintained, but some of the original atoms are replaced by other types of atoms. This can significantly influence the physical and chemical properties of the material, such as its electrical conductivity, melting point, and strength.

The other options describe different concepts. For instance, the first option suggests that solute atoms occupy interstitial spaces, which pertains to interstitial solid solutions, where smaller atoms fit into the spaces between larger atoms. The third option refers to temporary dipoles, which involve molecular interactions rather than the structural framework of metal alloys. Finally, the fourth option regarding alloying metals at the same ratio does not define a substitutional solid solution, as it is about the proportions used rather than the nature of how the solute and solvent elements interact within the crystal structure.