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- 1. Multiple ChoiceWhich of the following examples shows that a chemical reaction has occurred?A rock breaks into smaller pieces when it is struck with a hammer.Rust forms on a hammer that has been left outside to long.A cup of water turns pink when a few drops of red food coloring are added.A solid is formed when heat is removed from a sample of water.
- 2. Multiple ChoiceA student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles -could show that a gas is formingalways rise to the top of a liquid.are almost always perfectly spherical.usually burst after a few minutes.
- 3. Multiple Choice
Four students performed four different investigations by combining different substances. Their results are shown in the table provided. In which experiment are new substances being formed?Experiment 1Experiment 2Experiment 3Experiment 4 - 4. Multiple ChoiceHydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?The mass of the solution remains the same.Phase changes are observed.The color of the solution remains clear.The temperature of the solution increases.
- 5. Multiple ChoiceA clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?The level of the substance in the beaker is higher after the other liquid is added.A yellow solid forms and then settles to the bottom of the beaker.Small white crystals are left behind in the flask that held the first liquid.
- 6. Multiple ChoiceWhich of the following is an example that includes evidence of a chemical reaction?A sample of zinc is placed in water and it settles to the bottomA solid block of ice is heated and it completely melts into a liquid.Sugar that is burned gives off an odor and turns brown and then black.A tomato is placed into a blender and chopped up into smaller pieces.
- 7. Multiple ChoiceIn a container, a solid consisting of clear crystals is combined with a blue liquid and the following observations are obtained.
How many of the listed observations indicate a new substance was formed?1234 - 8. Multiple ChoiceEvidence of a chemical reactions is anything that shows -a new substance has formeda solid dissolved in a liquidinteraction between 2 gasesa change in the state of matter
- 9. Multiple ChoiceWhich of the following is NOT evidence that that a chemical reaction has occurred?produces light/heatproduction of a gasformation of a precipitatemelting
- 10. Multiple ChoiceFor an investigation a student poured a blue solution of CuSO4 into a beaker. The student placed a shiny, silver-colored strip of zinc metal in the solution and observed the changes.
The student inferred that a chemical reaction occurred. What evidence supports this inference?A dark solid formed on the zinc metal.
The zinc metal remained silver-colored and shinyThe CuSO4 solution turned blue when the zinc metal was added.None of these - 11. Multiple ChoiceWhich of the following equations demonstrates an actual chemical reaction that forms a new substance?ABCD
- 12. Multiple ChoiceWhich of these formulas contain equal numbers of nitrogen atoms?Formulas I and IIIFormulas I and IVFormulas II and IIIFormulas I, II, and V
- 13. Multiple ChoiceThe chemical formula for glucose, a simple sugar, is C6H12O6. The formula for ethanol is C2H6O. What accounts for the differences in these compounds?The elements that make up glucose are different than the elements that make up ethanolThe ratio of the elements is different in ethanol than in glucoseThe chemical properties of the elements are different in glucose and ethanolGlucose has more elements than the ethanol
- 14. Multiple ChoiceThe reactants are on the left side of the chemical equation.TrueFalse
- 15. Multiple ChoiceTwo clear colorless solutions were combined.
The student observed that the temperature changed from 25 •C to 23 •C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?One of the original compounds came out of solutionThe solutions reacted chemicallySome of the water froze into ice crystalsRapid evaporation of water occurred, leaving a solid - 16. Multiple Choice
How many atoms in all are in a molecule of serotonin?
C10H12N2O
2224254 - 17. Multiple ChoiceCoal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?The shape of the coal changesOxygen is presentA new substance is producedCoal is made up of more than one element
- 18. Multiple ChoiceA scientist performed four investigations using eight different liquids. In each investigation, the scientist combined two of the liquids under a fume hood and recorded observations in the table below.In which investigation is it least likely that the liquids reacted chemically?1234
- 19. Multiple Choice
Which of these is NOT a sign that a chemical change has occurred?
A loss of transparency
An unexpected color change
A temperature change
The formation of a precipitate
- 20. Multiple Choice
In a ___________change, a substance changes into a different substance.
Physical
Chemical
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