Explanation:

A substitutional alloy has metal atoms of different sizes that fit into the spaces left by the replaced atoms in a crystal lattice. Each atom fits exactly into the crystal structure as if it had always been there. The difference in atomic sizes can cause lattice distortion and changes in the physical properties of the alloy.

In a substitutional alloy, the solute atoms (smaller atoms) substitute or replace the solvent atoms (larger atoms) in the crystal lattice, occupying their positions in the lattice structure. The different atomic sizes introduce lattice strain and affect the overall properties of the alloy. Examples of substitutional alloys include brass (copper-zinc alloy) and sterling silver (silver-copper alloy).