Im not quite sure but it might be a or c... ill double check
Answer:
This question lacks options, the options are:
A. the number of days the rainwater was allowed to sit
B. the number of times the rainwater was observed
C. the change in the amount of rainwater due to evaporation
D. the change in pH of the rainwater over time
The answer is A
Explanation:
In an experiment, the independent variable is the variable that is changed or manipulated by the experimenter in order to effect a measurable response.
In this experiment, Austin is trying to determine how time changes the pH of standing rainwater. He collects rainwater and distributes it evenly in 5 jars, which he measured the pH at different days using a pH testing kit. Hence, the independent or manipulated variable is THE NUMBER OF DAYS THE RAINWATER WAS ALLOWED TO SIT before measuring their pH.
<span>D. Red photons have the least amount of energy.
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