What is the expected change in mass for a thoroughly dried sample?

• A. Less than 1%
• B. Less than 0.5%
• C. Less than 0.1%
• D. No change in mass

Answer: (C)

When a sample is thoroughly dried, the expectation is that any moisture content it contained has been fully evaporated, which would result in a minimal change in mass. In many analytical scenarios, especially in precise measurements, the goal is to achieve such a level of dryness that the remaining mass is virtually unchanged due to moisture loss.

The correct choice indicates a change of less than 0.1% in mass. This aligns with the notion that after thorough drying, the remaining moisture is negligible, significantly reducing the fraction of the total mass that is lost. In practice, if a sample is dried properly, the moisture content that remains, if any, is minimal to the point of being nearly unmeasurable on most scales.

While other options present possible mass changes, they reflect larger percentages that would typically occur with either incomplete drying or in scenarios where the sample composition varies significantly. Thus, the expectation of less than 0.1% change illustrates a highly efficient drying process, which is critical in contexts such as laboratory analysis and materials testing, where accuracy and precision are of utmost importance.