2. A. The things that stay the same from test A to test B to test C. B. The variable that is changed from test A to test B to test C. C. The thing that never changes. D. The thing that you measure.

3. A. The apple has more surface area than the tomato, which allowed the apple to float. B. The apple is more dense than the water, and the tomato is less dense than the water. C. The tomato is more dense than the water, and the apple is less dense than the water. D. The apple and the tomato have the same density, but the tomato skin absorbed water, making it sink.

4. A. 5 g/cm 3 C. 20 g/cm 3 B. 10 g/cm 3 D. 80 g/cm 3

5. A. water displacement method B. balance C. length x width x height D. centimeter ruler

6. A. mass. B. density. C. weight. D. solubility.

7. A. conductivity. B. magnetism. C. reactivity. D. flammability.

8. A. physical property B. reactivity C. chemical property D. flammability

9. A. has density and conductivity. B. has mass and takes up space (volume). C. can be seen. D. can be measured on a balance.

10. A. Scientific theories explain why something happens, and scientific laws describe what happens. B. Scientific theories require scientific evidence and scientific laws do not. C. Scientific theories are based on observation, and scientific laws are based on opinions. D. Scientific laws are frequently modified, but scientific theories are rarely changed as new information becomes available.

11. A. They are based upon feelings. B. They are based upon unguided guesses. C. They are based upon analysis of data. D. They are based upon careful planning of experimental design.

12. A. My shoe is size 8. B. My shoe is white. C. My shoe is dirty. D. My shoe is stinky.

13. A. protons and neutrons B. neutrons and electrons C. electrons and protons D. electron cloud and neutrons

14. A. a proton B. a neutron C. an electron D. an atom

15. A. A negatively charged central area surrounded by a positively charged cloud. B. A positively charged central area surrounded by a negatively charged cloud. C. A neutral central area surrounded by a negatively charged cloud.

16. A. The astronaut's mass on the Moon decreases. B. The density of the astronaut on the Moon is higher than on Earth. C. The atmosphere of the Moon affects the way the astronaut is able to move. D. The astronaut's weight on the Moon depends on the Moon's gravitational force.

17. A. Hydrogen Trioxide (H 3 O) B. Water (H 2 O) C. Carbon (C) D. Carbon Dioxide (CO 2 )

18. A. Compare the number of neutrons and electrons. B. Compare the number of neutrons and protons. C. Compare the number of protons and electrons. D. Compare the number of neutral particles and positive particles.

19. A. Sunscreen products do not work. B. The supporting scientific data are missing. C. The claim cannot be reevaluated when new information is reported.

20. A. Energy was removed from the water molecules. B. Attractions between the water molecules decreased. C. The volume of water was reduced. D. The water had undergone a chemical change.

21. A. element B. mixture C. compound D. homogeneous mixture