What is chemistry?

the study of living things and how they change

the study of matter and how it changes

the study of what living things are made of

the study of matter and how it moves

Which of the following is an eon in the time scale? phanerozoic proterozoic archean all of the above

Which of the following cell structures is significantly different between gram- positive and gram-negative bacteria?

Which of the following statements best distinguishes a hypothesis from a theory? a. theories are hypotheses that have been proved. b.hypotheses are guesses; theories are correct answers c. hypotheses usually are relatively narrow in scope; theories have broad explanatory power. d. theories are proved to be true; hypotheses are often contradicted by experimental results.