17. How many protons, neutrons, and electrons are present in an atom of sodium, Na, with a mass number of 23?
A. 11 protons, 11 neutrons, 11 electrons
B. 11 protons, 12 neutrons, 11 electrons
C. 23 protons, 11 neutrons, 12 electrons
D. 12 protons, 23 neutrons, 11 electrons

Iknow #2 is d. i just need to know why

This flow chart shows the amount of energy that is emitted by each type of light. ultraviolet > blue light > yellow light > red light (maximum energy) (minimum energy) in an experiment, shining which type of light on a strip of metal would be least likely to produce the photoelectric effect? ultraviolet light dim blue light bright red light bright yellow light

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of