Your teacher tells you, “Diseased tissue comes from unhealthy cells.” Which statement best explains why this information is true?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

Which part of earth’s surface receives the most direct rays from the sun? a) equator b) ocean c) poles d) mountains