Final answer:
Steel is the correct answer as it is not a metallic element but an alloy primarily composed of iron, whereas Lithium, Nickel, and Copper are all metallic elements.
Step-by-step explanation:
The student is asking which of the given options is not a metallic element. The options provided are Lithium (Li), Nickel (Ni), Steel, and Copper (Cu).
- Lithium (Li) is classified as a metal.
- Nickel (Ni) is also a metal, specifically a transition metal.
- Copper (Cu) is a metal and a transition metal as well.
- Steel, however, is not an element but an alloy, which is a mixture of iron (element) with other elements, usually carbon.
Therefore, the correct answer is c) Steel, which is not a metallic element but an alloy composed of multiple elements including primarily iron.