Final answer:
The independent variable in the hypothesis regarding the plant wilting is the amount of water the plant is receiving. In the detergent and soil experiment, the mistake is the introduction of two independent variables: detergent in the soil and differing sunlight exposure.
Step-by-step explanation:
When discussing the hypothesis that if you water a large plant in a 5-gallon pot with 2 tablespoons of water every hour for 5 days it will start to wilt, the independent variable is the amount of water the plant is receiving. In an experiment, the independent variable is the factor that is changed or controlled by the scientists to test the effects on the dependent variable. In the scenario given, the change in watering amount, in this case, 2 tablespoons of water per hour, is what is being manipulated to observe the effect on plant health, such as wilting.
As for the flawed experiment involving detergents in the soil, the mistake is that the student has introduced two independent variables: the presence of detergent in the soil and the amount of sunshine (sun vs. shade). For a controlled experiment, one should change only one independent variable at a time to determine its specific effect on the dependent variable. In this case, the experiment should have all seed pots in either sun or shade conditions, not a mix of both, to solely test the effect of detergent on the growth of plants.