Final answer:
Francium, uranium, aluminum, and nickel are all metals; francium is an alkali metal, uranium is an inner transition metal, aluminum is a representative metal, and nickel is a transition metal.
Step-by-step explanation:
The elements Fr (francium), U (uranium), Al (aluminum), and Ni (nickel) are all considered metals. Specifically, Fr is an alkali metal, found in Group 1 of the periodic table, which includes highly reactive metals such as lithium, sodium, and potassium. U (uranium) is an inner transition metal, also known as an actinide. Al (aluminum) is a representative metal, notable for its use in items such as cookware and foil, and it is known for forming a protective oxide coating that helps prevent further reaction with air. Lastly, Ni (nickel) is a transition metal, characterized by its use in alloys and its catalytic properties.