The variable the researchers intentionally varied in the experiment is time and the units of the variable is mins.
What is an independent variable?
The independent variable is the variable that the researcher varies or changes or manipulates in the course of the experiment. The independent variable usually have a direct effect on the dependent variable.
With the passage of time, the level of concentration increases. This means that time is the independent variable and concentration is the dependent variable.
Please find the required table attached.
To learn more about independent variables, please check: brainly.com/question/26287880
