Structure of Metals and Alloys Practice Test

A student compares pure aluminum (Al) to an alloy made by mixing Al with a small amount of magnesium (Mg). Both solids are metallic. Which statement best describes what happens to the valence electrons in the alloy compared with pure Al?

A jeweler compares pure gold (Au) with 18-karat gold, an alloy containing Au mixed with Ag and Cu. The alloy is still metallic with delocalized electrons, but the atoms are not all identical. Which statement best predicts why 18-karat gold is often preferred for jewelry compared with pure Au?