Which of the following statements is true?
a. calcium and potassium are good for your body.
b. most of the atmosphere is made of oxygen and helium.
c. the center of an atom is made of protons and electrons.
d. all of the above.

Which organic molecule is found in the chromatin of cells?

Five students had to answer the question how are elements arranged in a periodic tabledamon: i think the elements are arranged by increasing massflo: i think the elements are arranged according to their properties sienna: i think the elements are arranged by when their discovers kyle: i think the elements are arranged according to how common they areglenda: i don't agree with any of themwho is right

An electron moved from shell n = 2 to shell n = 1. what most likely happened during the transition? a fraction of a photon was added. a photon of energy was absorbed. a fraction of a photon was removed. a photon of energy was released.