Answer: TWO.
At least two groups: treatment group and control group.
The treatment group is that is exposed to the different levels of the independent variable ( a medication for example), while the control group is not treated, so the researchers can compare the effect of the medication.
Answer:A double convalescent bond is where two pairs of electrons are shared between the atoms rather than just one pair. Two oxygen atoms can both achieve stable structures by sharing two pairs of electrons as in the diagram.
Explanation:
