Answer:
In scientific experiments, a control is a standard or reference point used to compare and evaluate the results of the experiment. In the context of water solutions, they may be considered controls if they are used to provide a baseline measurement of a specific variable of interest, such as pH or the presence of certain minerals or contaminants.
For example, in a study examining the effects of new water treatment on water quality, researchers may test samples of untreated water as a control to compare with the treated water samples. The untreated water serves as a baseline measurement to determine the extent of any changes or improvements resulting from the treatment.
Similarly, in a study examining the effects of a certain substance on aquatic organisms, researchers may expose the organisms to water solutions containing varying concentrations of the substance, as well as a control solution without the substance. The control solution serves as a baseline measurement to compare the effects of the substance on the organisms.
In both of these examples, the water solutions used as controls are considered essential components of the experimental design to help ensure accurate and meaningful results.
Step-by-step explanation: