1. How many different elements are involved in the reaction shown above?
C1: Matter and Energy
TEK 6.5C
11-1
C3H8 + 5O2 → 3CO2 + 4H2O
How many different elements are involved in the reaction shown above?

2. C1: Matter and Energy
TEK 8.5A
8.3B
11-2
Which of these best describes one of the subatomic particles that could be found at location X in the model of an atom shown above?
A) It has mass but no charge.
B) It has no mass and a positive charge.
C) It has a large mass and a negative charge.
D) It has no mass and an equal number of positive and negative charges.

3. C1: Matter and Energy
TEK 8.5C
11-3
An element has a metallic-gray appearance. It also has the properties of both a metal and a nonmetal. In which section of the periodic table indicated above would the element most likely be found?

4. C1: Matter and Energy
TEK 8.5E
8.2A
11-4
A student observes some sugar as it is heated and burns. The student concludes that a chemical reaction has occurred. Which of the following observations about the burning sugar provides evidence of a chemical reaction?
A) Heat is added to the sugar crystals.
B) The sugar melts and becomes a liquid.
C) The temperature of the sugar increases.
D) Gas is produced as the sugar turns black.

5. C1: Matter and Energy
TEK 6.6B
8.4A
13-02
A balance and a graduated cylinder are used to determine the density of a mineral sample. The sample has a mass of 14.7g and a volume of 2.2cm3. What is the density of the mineral sample?
A) 0.15g/cm3
B) 32g/cm3
C) 13g/cm3
D) 6.7g/cm3

6. C1: Matter and Energy
TEK 8.5C
13-05
A researcher wants to experiment with an element that reacts like phosphorus (P) but has a greater atomic mass. Which element should the researcher select for the experiment?
A) Nitrogen (N)
B) Sulfur (S)
C) Arsenic (As)
D) Silicon (Si)

7. C1: Matter and Energy
TEK 8.5B
8.3B
13-11
An atom of which element is represented by this model?
A) Boron (B)
B) Carbon (C)
C) Neon (Ne)
D) Sodium (Na)

8. Which of the following best describes an electron?
C1: Matter and Energy
TEK 8.5A
13-15
Which of the following best describes an electron?
A) It has no charge and about the same mass as a proton.
B) It has a negative charge and much less mass than a proton.
C) It has a positive charge and much more mass than a neutron.
D) It has a negative charge and about the same mass as a neutron.

9. C1: Matter and Energy
TEK 8.5E
8.1A
13-18
A scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO3) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?
A) The baking soda and hydrochloric acid combined, and bubbles formed.
B) The baking soda absorbed the hydrochloric acid.
C) Some of the baking soda dissolvedinthehydrochloric acid.
D) Thehydrochloric acid evaporated, leaving only the baking soda.

10. C1: Matter and Energy
TEK 8.5d
13-20
Which information could a student determine from only the chemical formula of a protein?
A) The color of the protein
B) The number of molecules in each sequence that makes up a protein
C) Thephysicalarrangement ofatomsinthestructureoftheprotein
D) The number of atoms of each element in the protein

11. C1: Matter and Energy
TEK 8.5F
13-23
A teacher asks a student to write the chemical equation for photosynthesis. The student’s response is shown below.
The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?

12. C1: Matter and Energy
TEK 7.6A
13-31
Hay is made up of organic compounds. What are the main elements in many organic compounds?
A) helium, carbon, sodium
B) sodium, hydrogen, nitrogen
C) carbon, hydrogen, oxygen
D) radon, oxygen, helium

13. C1: Matter and Energy
TEK 8.5B
13-33
When trying to identify an unknown element, a scientist determines what other elements the unknown element reacts with chemically. Which property of the unknown element determines the other elements it reacts with?
A) The total number of neutrons in the unknown element
B) The total number of particles in the nucleus of the unknown element
C) The number of protons in the nucleus of the unknownelement
D) The number of valence electrons in the unknown element

14. The model of the periodic table shows the locations of four elements.
C1: Matter and Energy
TEK 8.5C
8.3B
13-37
The model of the periodic table shows the locations of four elements.
A student is asked to identify an element that is a pale-yellow brittle solid and does not conduct electricity. At which location in this periodic table would the element most likely be found?

15. C1: Matter and Energy
TEK 8.5A
13-40
An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom’s nucleus?
A) +25
B) +30
C) −25
D) −30

16. How many atoms of oxygen are in a molecule of glucose (C6H12O6)?
C1: Matter and Energy
TEK 8.5D
8.3B
13-44
How many atoms of oxygen are in a molecule of glucose (C6H12O6)?

17. C1: Matter and Energy
TEK 8.5C
13-48
The chemical equation shown below represents a reaction that produces fuel for certain cars.
Which substance represented in this equation is classified as an element?
A) CO
B) H2O
C) CO2
D) H2

18. C1: Matter and Energy
TEK 8.5E
8.2E
13-52
During an investigation, a student combined the two clear, colorless solutions. 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?
A) One of the original compounds came out of solution.
B) The solutions reacted chemically.
C) Some of the water froze into ice crystals.
D) Rapid evaporation of water occurred, leaving a solid.

19. C1: Matter and Energy
TEK 7.6B
14-06
Many processes occur in the digestive system. Which process is best classified as a physical change?
A) Saliva converting the starch molecules in crackers into simple sugars
B) Digestive enzymes breaking down proteins into smaller fragments
C) Bacteria converting lactose into simple sugars in the intestines
D) Teeth grinding an almond into smaller pieces in the mouth

20. C1: Matter and Energy
TEK 8.5E
8.2E
14-10
Some students in a chemistry lab conducted an investigation in which they added four different solid substances to separate beakers of water. They stirred the mixtures for one minute and then recorded their observations in the table below.
Which substance most likely caused a new substance to be formed when mixed with water?

21. C1: Matter and Energy
TEK 7.5C
8.3B
14-14
The flow of energy in some Australian food chains is modeled in the energy pyramid.
Based on the model, which consumers would receive the greatest amount of energy captured by the producers in their food chains?
A) Wedge-tailed eagles
B) Chuditch
C) Ring-tailed opossums
D) Eucalyptus trees

22. C1: Matter and Energy
TEK 8.5B
14-16
A student is studying calcium, a highly reactive element that humans need for strong bones. Which characteristic of calcium is most closely related to its chemical reactivity?
A) The 20 protons in each atom of calcium
B) The density of calcium, which is g/cm3
C) The atomic mass of calcium, which is amu
D) The 2 valence electrons in each atom of calcium

23. C1: Matter and Energy A model of a beryllium atom is shown.
TEK 8.5A
8.3B
14-19
A model of a beryllium atom is shown.
What types of particles are found in the cloud surrounding the atom’s nucleus?
A) Positively charged particles and negatively charged particles
B) Negatively charged particles only
C) Neutral particles and positively charged particles
D) Positively charged particles only

24. C1: Matter and Energy
TEK 7.6A
14-21
Based on its chemical formula, which of the following substances is an organic compound?
A) Urea, CH4N2O
B) Ammonium Sulfide, (NH4)2s
C) Silane, SiH4
D) Sodium Chloride, NaCl

25. C1: Matter and Energy
TEK 6.5C
8.3B
14-25
In the chemical reaction shown above, the products are best classified as —
A) two elements
B) one element and one compound
C) two compounds
D) two compounds and one element

26. C1: Matter and Energy
TEK 8.5D
14-31
The chemical formula for sodium sulfate is Na2SO4.
How many sulfur atoms are in the formula for sodium sulfate?
A) 1
B) 2
C) 6
D) 7

27. What is the mass number of a potassium (K) atom that has 20 neutrons?
C1: Matter and Energy
TEK 8.5A
14-33
What is the mass number of a potassium (K) atom that has 20 neutrons?
A) 18
B) 19
C) 20
D) 39

28. C1: Matter and Energy
TEK 8.5E
8.2E
14-39
A 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?

29. How many atoms in all are in a molecule of serotonin?
C1: Matter and Energy
TEK 8.5D
14-44
Serotonin is a chemical substance that acts as a neurotransmitter. It helps relay messages in the human brain. The formula for one molecule of serotonin is shown below.
C10H12N2O
How many atoms in all are in a molecule of serotonin?

30. C1: Matter and Energy
TEK 8.5C
8.3B
14-46
A student is studying the ways different elements are similar to one another. Diagrams of atoms from four different elements are shown. Which two atoms are of elements in the same group in the periodic table?
A) Atom 1 and Atom 2
B) Atom 1 and Atom 4
C) Atom 2 and Atom 3
D) Atom 3 and Atom 4

31. C1: Matter and Energy
TEK 6.6A
8.2E
14-48
Some students conducted a laboratory investigation to learn more about the physical properties of different elements. They observed four samples and recorded their observations in the table.
Based on these observations, which sample is most likely a nonmetal?

32. C1: Matter and Energy
TEK 8.5B
14-51
The table lists three characteristics of an atom of an element.
An atom of which element is described by the data in the table?
A) Radon (Rn) B) Cadmium (Cd)
C) Rubidium (Rb) D) Astatine (At)

33. C1: Matter and Energy
TEK 8.5E
15-9
Coal 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?
A) The shape of the coal changes.
B) Oxygen is present.
C) A new substance is produced.
D) Coal is made up of more than one element.

34. C1: Matter and Energy
TEK 8.5B
15-11
The atoms of a certain element each contain 11 protons and 1 valence electron. Which statement correctly identifies this element and describes its chemical reactivity?
A) The element is sodium, and it is highly reactive.
B) The element is fluorine, and it is not very reactive.
C) The element is sodium, and it is not very reactive.
D) The element is fluorine, and it is highly reactive.

35. C1: Matter and Energy
TEK 6.6B
8.2E
15-15
For an investigation a student records data about four unknown substances. The student then calculates the densities of the unknown substances and compares them with the table of densities of known substances shown. Which unknown substance is most likely carbon?

36. C1: Matter and Energy
TEK 8.5A
15-17
An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is a very stable gas. How many neutrons are in this atom?

37. All the following reactions are correctly balanced except—
C1: Matter and Energy
TEK 8.5F
15-22
All the following reactions are correctly balanced except—
A) 2C2H2 + 5O2 → 4CO2 + 2H2O
B) 4Fe + 3O2 → 2Fe2O3
C) NaHCO3 → Na2CO3 + H2O + CO2
D) 2CH3OH + 3O2 → 2CO2 + 4H2O

38. C1: Matter and Energy
TEK 8.5C
15-24
The periodic table is organized into groups and periods of elements. The characteristics of a certain group of elements are listed. Which of these elements is in this group?
A) Lithium B) Strontium C) Aluminum D) Silicon

39. Which of these formulas contain equal numbers of nitrogen atoms?
C1: Matter and Energy
TEK 8.5D
15-27
Which of these formulas contain equal numbers of nitrogen atoms?
A) Formulas I and III
B) Formulas I and IV
C) Formulas II and III
D) Formulas I, II, and V

40. C1: Matter and Energy
TEK 6.6A
15-33
Aluminum, sulfur, and chlorine are elements found on the periodic table. Tests involving these three elements would show that at normal room temperature —
A) sulfur is malleable and aluminum conducts electricity
B) chlorine is malleable and conducts electricity
C) aluminum is malleable and conducts electricity
D) all three elements are malleable and conduct electricity

41. C1: Matter and Energy C6H12O6 + 6O2 6CO2 + 6h2O + energy
TEK 8.5D
15-36
C6H12O O CO2 + 6h2O + energy
The equation represents a chemical reaction that occurs in living cells. How many atoms are represented in the reactants of this equation?
A) 6 B) 12 C) 24 D) 36

42. C1: Matter and Energy
TEK 8.5B
15-39
A chemist is identifying the elements present in a sample of seawater. What characteristic of an element’s atoms always determines the element’s identity?
A) The number of protons
B) The number of neutrons
C) The location of valence electrons
D) The number of valence electrons

43. C1: Matter and Energy
TEK 8.5A
8.3D
15-45
In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of an atom. His discovery led to the understanding that an atom consists mostly of empty space with —
A) protons orbiting a dense nucleus made of electrons and neutrons
B) electrons orbiting a dense nucleus made of protons and neutrons
C) neutrons and protons orbiting a cloud of electrons
D) electrons and protons orbiting a cloud of neutrons

44. C1: Matter and Energy
TEK 8.5E
8.2A
15-48
For 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) A dark solid formed on the zinc metal.
B) The zinc metal remained silver-colored and shiny.
C) The CuSO4 solution turned blue when the zinc metal was added.
D) None of these

45. Which two elements on the periodic table are in the same period?
C1: Matter and Energy
TEK 8.5C
15-51
Which two elements on the periodic table are in the same period?
A) Sn and Rb
B) F and Cl
C) K and Ba
D) Se and Te

46. C1: Matter and Energy
TEK 8.5D
15-54
In which of these compounds are there twice as many oxygen atoms as hydrogen atoms?
A) H3PO4
B) H2SO4
C) HClO3
D) H2O