Answer:
10g
Step-by-step explanation:
The amount of copper in the heated mass of the new substance produced is still 10g because in any chemical action, mass is always conserved.
- According to the law of conservation of matter "matter is neither created nor destroyed in a chemical reaction".
- The change in mass is only due to oxygen gas that combines with the new copper formed or other substances that joined the mass.
- The substance will still have the same amount of copper as the original one.
- Since we started with 10g of copper, we end with 10g of copper.