dichotomous keys are used to identify organisms based on their observed characteristics. dichotomous means.. a. a list of organism names b. a confusing list of questions c. to classify d. divided into two parts

Dichotomous keys consist of a series of statements with two choices in each step that will lead users to the correct identification. So I believe your answer would be A.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.