The atomic mass of an element is the weighted average mass of the isotopes of that element. (true or false)
atoms with the same number of protons but different number of neutrons are called what? (choices: _isotopes, ions , iosomers)
how many neutrons are in potassium-40? the chemical symbol for potassium is k.
(choices: _19,20,21,40))

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