The brightness of a star depends on its a. color b. composition of atmosphere c. distance from Earth, and stars that are closer look a. brighter b. dimmer c. white

Either B or C. Composition or the Distance from the Earth.

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.