Q: Pure substances have a constant composition and can only be changed through what? Choices: - heating - dissolution - liquid reactions - chemical reactions A:
chemical reactions

Q: Scientists use the principles of what to make predictions, which they then test? Choices: - their teachers - their guesses - their faith - their hypothesis A:
their hypothesis

Q: What theory can explain virtually all the properties of metals? Choices: - property law theory - formation theory - bonding theory - band theory A:
band theory