Having a control in an experiment allows you to see what happens when no variables are changed. If you do not have a control, you do not have anything to compare your results with after changing variables of the experiment.
In any experiment there are two groups set up. One is called the control group (sample with normal characteristics) and the other is the experimental group. Control group is also sometimes called placebo.
Adjustment knobs are used to focus light in a light microscope.
stimulus
use eye wash station
Because it is as old as stone itself.
Lyndon B. Johnson
It is not safe to drink or eat chemicals.
A reactant is a substance that participates in and changes during a reaction.