Question

What factor was manipulated in the experiment? (What is the independent variable being tested?)
Different temperatures of water
Amount of smoke particles added
Amount of cloud formed

Answer 1

The factor that was manipulated in the experiment is the "different temperatures of water." This is the independent variable being tested, as it is the variable that the experimenter changes to observe its effect on the dependent variable (in this case, likely the amount of cloud formed or the behavior of the smoke particles).