In scientific investigations, identifying potential sources of error and confounding variables is critical to ensuring the validity of experimental results. Match each experimental scenario to the primary uncontrolled confounding variable that threatens the validity of its results.
- Testing how fertilizer amount affects plant growth by placing fertilized plants in a sunny window and unfertilized plants in a dark closet.Differences in sunlight exposure between the experimental groups.
- Measuring the boiling point of salt water across multiple trials, where tap water is used in some trials and distilled water is used in others.Variations in the purity of the water solvent used.
- Comparing how fast ice melts on different surfaces, where some trials are conducted in an air-conditioned room and others are conducted outdoors.Differences in surrounding ambient temperature during the trials.
Answer
The plant growth experiment matches with differences in sunlight exposure; the salt water boiling experiment matches with variations in water purity; and the ice melting experiment matches with differences in ambient temperature.
Each correct pairing links an experimental setup that fails to keep a background condition constant with the specific environmental or chemical factor that was allowed to vary.
Step-by-Step Solution
Key Concept
Identifying Sources of Error and Confounding Variables