1. Does the following diagram represent a chemical or physical change? How do you know? Be sure to explain your answer.

Select all of the statements which are true. electrons are located in shells or orbits around the atom. electrons orbit slowly around the atom. electrons travel in one flat path around the nucleus of an atom. the valence of an atom is determined by the number of electrons in the atom's outermost shell.

Which are forms of frozen water? check all that apply. dew frost hail rain sleet

Give one example of a pure (exact) number and of an estimated (measured) number.