A student heats a sample of copper(II) carbonate in a crucible. The student records the mass of the solid remaining inside the crucible every minute.
| Time / minutes | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|---|
| Mass of solid remaining / g | 6.0 | 5.1 | 4.4 | 4.0 | 3.9 | 3.9 | 3.9 | 3.9 |
Explain the trends shown by the data in the table.