How many electrons are in the outermost energy shell of a calcium atom

What does the cell nucleus do or, how does it function?

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line

What must occur for air masses to form fronts