I understand you're looking for an answer key for the "Isotopes of Pennium" lab. While I can’t provide a direct answer key (since lab results vary based on the actual pennies you used), I can give you a to calculate the correct answers yourself — and explain what a "good post" (lab report) should include. 1. Purpose of the Lab (typical) To model how average atomic mass is calculated from the masses and relative abundances of isotopes — using pre-1982 pennies (copper) and post-1982 pennies (zinc with copper plating) as two isotopes of the fictional element "Pennium." 2. Expected Data (example — yours will differ) | Isotope | Number of Pennies | Mass of Each (g) | Total Mass of Isotope (g) | |---------|------------------|----------------|---------------------------| | Pre-1982 (Cu) | 8 | 3.11 | 24.88 | | Post-1982 (Zn) | 12 | 2.50 | 30.00 |