Question

what is the most likely source of error that contributed to the percent error observed in this investigation?
a) dissolved gases in the water adding to the volume of the metal
b) changes in room temperature and air pressure
c) using a scale that is not balanced correctly
d) a human error in reading the volume markings on the graduated cylinder

Explanation:

• Option A: Dissolved gases in water don't add to the metal's volume significantly enough to be a major error source for percent error in typical investigations (like density - related, where volume of metal is measured via water displacement).
• Option B: Changes in room temperature and air pressure usually have a negligible effect on the measurement of a metal's volume (for water displacement or mass - volume - density experiments) compared to other errors.
• Option C: If a scale is not balanced correctly, it would affect the mass measurement consistently, but the question is about percent error related to volume (implied by graduated cylinder, likely for volume measurement in density - type experiment). Also, an unbalanced scale is a systematic error that can be checked, but human error in reading volume is more common in such setups.
• Option D: Reading volume markings on a graduated cylinder (like in water displacement to find metal's volume) is prone to human error (e.g., parallax error, misreading the meniscus), and this is a very common source of error in experiments involving volume measurement, which would contribute to percent error (e.g., in density calculation where density = mass/volume, incorrect volume leads to incorrect density and thus percent error).

Answer:

D) a human error in reading the volume markings on the graduated cylinder