Final answer:
Pennies after 1982 are likely made of zinc (Zn) due to changes from the original copper (Cu) material used before 1982, influenced by the cost of copper.
Step-by-step explanation:
Based on experimental data, it is likely that the metal used to make pennies after 1982 is zinc (Zn). This is because before 1982, pennies were made primarily of copper (Cu), but in 1982, the composition was changed to a predominantly zinc core with a thin copper plating.
This change was due to the rising cost of copper at the time. The mention of a pre-1982 copper penny containing approximately 3 × 10²² copper atoms indicates that post-1982 pennies have a different composition, as copper is now only a minor component of the penny's total mass. The remaining options, iron (Fe) and aluminum (Al), are not known for being primary materials for penny manufacturing after 1982.