How can flame color identify an unknown metal? How can a spectrum positively identify an element?
How can astronomers tell which elements a star contains without a sample of it?

6what is the importance of water on earth? a) it keeps the top layer of the geosphere cool b) it allows life to exist c) it provides ice at the poles d) it creates earth's blue color from space

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?