Chemistry Exam First Semester 2007/2008
1. If a student’s hand is accidentally exposed to an acidic solution, what should be done? A. Rinse the hand in a concentrated base.
B. Rinse the hand in running water.
C. Wrap the hand in paper towels.
D. Cover the hand with oil.
2. A student was instructed to carry out an experiment that illustrates the law of conservation of mass. The teacher indicated that the experiment should be carried out three times. The student plans to report the average of the three results. What can the student do to maximize the reliability of the data collected? A. Report the result that came closest to the class average. B. Conduct each trial using the same balance. C. Report the average of the two most similar values only. D. Perform each of the trials on different days.
3. When examining the physical properties of an unknown substance, which of the following characteristics is unsafe to observe? A. Color B. Weight C. Form D. Taste
4. For an experiment, 9.7 mL of HCl are needed. What is the best instrument to use for measuring this volume? A. Beaker
B. Erlenmeyer flask
C. Graduated cylinder
D. Test tube
5. To remove the sand first and then the salt from a mixture of sand and salt water, one combination of techniques you could use would be to first — A. evaporate and then distill
B. evaporate and then condense
C. filter and then evaporate
D. filter and then condense
6. Soda water is a solution of carbon dioxide in water. This solution is composed of a — A. gaseous solute in a gaseous solvent B. liquid solute in a liquid solvent C. gaseous solute in a liquid solvent D. liquid solute in a gaseous solvent
7. A student designed this experiment to study the effects of a catalyst on a reaction. Which trial serves as the experimental control? A. 1 B. 2 C. 3 D. 4
8. Which of the following states of matter has a definite shape and volume? A. Solid B. Liquid C. Gas D. Plasma
9. Which state of matter has an indefinite shape but a definite volume? A. Solid B. Liquid C. Gas D. Plasma
10. Which state of matter takes the shape and volume of its container? A. Solid B. Liquid C. Gas D. Plasma
11. Which numbered process represents condensation? A. 1 B. 2 C. 3 D. 4
12. Which state of matter is the most common in the universe? A. Solid B. Liquid C. Gas D. Plasma
13. When solid changes to a liquid it is a A. chemical change
B. physical change
C. nuclear change
D. sublamination change
Identify the diagrams representing matter below. Use the key to record your answer.
a. Compound b. Diatomic molecule (element) c. Individual atoms (element)d. Mixture (elements and compounds together)
14. / 15. / 16. / 17.
Use the Multiple choice selections above the pictures to identify the pieces of equipment pictured below it.
a. Beaker b. Crucible and lid c. Erlenmeyer Flask d. Crucible Tongs18. / 19. / 20. / 21.
Multiple choice: Select the best answer and record its letter on your answer sheet.
22. Round the measurement 98.473 L to three significant figures. a. 98.4 L
b. 98.5 L
c. 0.473 L
d. 98.0 L
23. Which of these series of units is ordered from smallest to largest? a. µg, cg, mg kg
b. µs, ns, cs, s
c. mm, dm, m, km
d. nL, mL, dL, cL
24. How many significant figures are in the following measurement, 47.70 g of copper? a. 1 b. 2 c. 3 d. 4
25. Given the following calculation (3.56 x 1026 mm) x (3.56 x 1022 mm) x (3.56 x 106 mm). The correct units for the problem is
a. mm
b. mm2
c. mm3
d. there are no units
26. A graduated cylinder contains 44.2 mL of water. A 48.6 g piece of metal is dropped into the cylinder. When the metal is completely covered with water, water raises to the 51.3 mL mark. What is the density of the metal?
a. 0.95 g/mL
b. 71. g/mL
c. 6.8 g/mL
d. 0.15 g/mL
27. Which of these measurements has four significant figures? I . 3.045 g II. 0.0450 g III. 3.0 x 104 g IV. 4.050 g
a. I and III only b. II and IV only c. I and IV only d. I, II, and IV only
28. Steven measured out 250 L of hydrochloric acid. Express this number in scientific notation. (Remember significant figures) a. 250 x 10 L
b. 2.50 x 102 L
c. 2.5 x 102 L
d. 250 x 103 L
29. Amanda was running at a rate of 5.00 km/hr. Convert her rate to m/s. a. 1.39 m/s
b. 5 x 103 m/s
c. 8.33 m/s
d. 83.3 m/s
30. Erika measured out 247 mg of silver nitrate with an analytical balance. Convert this measurement to grams (g).
a. 247 x 103 g
b. 2.47 x 10-1 g
c. 2.47 x 10-2 g
d. 2.47 x10-3 g
31. The density of lead is 11.35 g/ml. What is the density in kg/L? a. 11.35 kg/L
b. 1.135 x 104 kg/L
c. 1.135 x 10-4 kg/L
d. 1.135 x 106 kg/L
32. Rusty measured the room temperature to be 22 oC. What is the temperature in Kelvin? a. 295 K b. 251 K c. 493 oK d. 53 K
33. A student used the above ruler to measure the length of a nail. The length of this nail, according to the precision of the ruler, is — a. 3.5 cm
b. 3.55 cm
c. 3.7 cm
d. 3.75 cm
34. How is 0.00124 expressed in proper scientific notation? a. 1.24 x 10-3
b. 0.124 x 10-2
c. 1.24
d. 1.24 x 103
35. A student measures the mass of a piece of copper three times and records the results in the following table:
The actual mass of the copper is 28.7 grams. Which of the following is demonstrated in the student’s data?
a. Accuracy
b. Continuity
c. Precision
d. Reliability
36. Measurement 1: 5.2 g Measurement 2: 5.4 g Measurement 3: 3 g Measurement 4: 2.45 g These data show repeated measurements of the same object which has a known mass of 5.38 grams. Which measurement is most accurate?
a. 1 b. 2 c. 3 d. 4
37. The mass of an object was recorded as 9.93 g, 9.90 g, and 10.02 g, using an electronic analytical balance. What is the average of these three masses expressed to the correct number of significant figures?
a. 9.9 g
b. 9.95 g
c. 10.0 g
d. 10.00 g
38. To determine the density of corn syrup, a student poured 3.0 mL of the liquid into a 10.0 mL graduated cylinder and massed the cylinder and contents. He determined the density to be 10.5 g/cm3. The accepted value for the density of corn syrup is 1.38 g/cm3. The most probable cause of error was that —
a. the mass and the volume were multiplied b. the mass of the cylinder was included in the density formula
c. the graduated cylinder accuracy is only 0.5 mL d. the mass and volume were inverted in the density formula
39. According to the above data, which of the following represents the average density for sample X using the correct number of significant figures? a. 1 g/mL
b. 0.8 g/mL
c. 0.81 g/mL
d. 0.821 g/mL
40. The density of an unknown metal was determined to be 2.85 g/mL. The actual density was 2.70 g/mL. What is the percent error in this determination? a. 0.056%
b. 0.15%
c. 5.6%
d. 94.4%
41. Which of these shows a volume of 1.25 liters expressed in milliliters?
a. 125 mL
b. 12.5 x 101 mL
c. 1.25 x 102 mL
d. 1.25 x 103 mL
42. Which of the following best describes why an experiment should be repeated? a. to organize the data
b. To produce a variety of results
c. To include another variable
d. To verify the observed results
43. A student wanted to obtain a very accurate value for the volume of a piece of steel. He filled a 100.0 cm3 graduated cylinder to the 50.0 cm3 mark with water. After he carefully dropped the steel into the cylinder, the water level rose to the 55.6 cm3 level. He reported the volume of the steel as 5.6 cm3. How could the student improve the reliability of his analysis? a. Report the volume as 56 mm3 b. Fill the graduated cylinder to the 70.0 cm3 mark before adding the steel b. Mass the steel and report its density in g/cm3 d. Repeat the measurement many times and report an average value
44. First Measurement: 6.293 g Second Measurement: 6.294 g Third Measurement: 6.295 g A student obtained these data after measuring the mass of an object three different times. If the true value of the object’s mass is 5.550 g, these data are best described as - a. precise but not accurate b. accurate but not precise c. accurate and precise d. neither accurate nor precise
45. The SI unit for the amount of a substance is a. kilogram b. gram c. mole d. liter
Trial / Mass (g) / Volume (cm3) / Density (g/cm3)1 / 14.5 / 2.52 / 5.75
2 / 28.3 / 4.48 / 5.90
3 / 33.1 / 5.75 / 5.76
4 / 55.4 / 9.62 / 5.76
46. A team of chemistry students made the above measurements and density calculations of the same type of material. The accepted value (true or known value) of the density of the material was 5.72 g/cm3. Which trial has the least amount of absolute error? a. 1 b. 2 c. 3 d. 4
Perform the following math operations.
47. Add the following numbers: 1.20 x 103 + 2.8 x 102 a. 4.00 x 105
b. 1.48 x 103
c. 1.48 x 102
d. 4.00 x 102
48. Multiply the following numbers with units: (2.5 x 102 cm)(2.0 x 10-4 cm) a. 5.0 x 10-6 cm
b. 5.0 x 102 cm2
c. 5.0 x 10-2 cm2
d. 5.0 x 10-8 cm
49. Convert 2.0 x 103 cm to meters. a. 2.0 m
b. 2.0 x 103 m
c. 2.0 x 106 m
d. 200 m
e. no answer is correct
50. The density of oxygen gas at STP is 0.00143 Kg/L to g/mL. a. 1.43 g/mL
b. 0.143 g/mL
c. 0.0143 g/mL
d. 0.00143 g/mL
Match the diagram with the best answer in the key below.
Key: A. accurate and precise
B. Accurate but not precise
C. Not Accurate but Precise
D. Not Accurate nor Precise
51. / 52. / 53. / 54.55. A neutral atom of aluminum-27 contains- a. 13 protons and 27 electrons
b. 14 protons and 13 neutrons
c. 13 electrons, 13 protons, and 14 neutrons
d. 13 electrons, 14 protons, and 13 neutrons
56. The element chlorine exists as two naturally occurring isotopes. Chlorine-35 occurs 75% of the time and Chlorine-37 occurs 25% of the time. Which of the following calculations should be used to calculate the correct average atomic mass of chlorine?
57. How many protons, neutrons, and electrons are in a neutral atom of sodium-23? a. 11 p+, 12 no, 11e- b. 11 p+, 11 no, 12e- c. 12 p+, 11 no, 12e- d. 12 p+, 11 no, 11e-
58. Which scientist was the first to conclude through experimentation that atoms have positive charges in their nuclei? a. Bohr
b. Dalton
c. Mosley
d. Rutherford
59. Which of the following describes what takes place when iron (Fe0) is oxidized to Fe2+ ions? a. A gain of two electrons
b. A loss of two electrons
c. A gain of two protons
d. A loss of two protons
60. Which of these conclusions can be drawn from Rutherford’s experiment? a. Each atom contains electrons. b. The nucleus of an atom can be split. c. Each atom contains protons. d. Atoms are mostly empty space.
61. Radioactive iodine-131 has a half-life of eight days. The amount of a 200.0 gram sample left after 32 days would be — a. 6.25 g
b. 12.5 g
c. 25.0 g
d. 50.0 g
62. How does the radioactive isotope Carbon-14 differ from its stable counterpart Carbon-12? a. It has a different number of protons and two less neutrons than C-12. b. It has the same number of protons and two more electrons than C-12. c. It has the same number of protons but two more neutrons than C-12. d. It has a different number of protons and two more neutrons than C-12
63. Atoms of the same element must — a. contain the same number of neutrons b. have the same mass number c. contain the same number of protons d. have equal numbers of protons and neutrons
64. Which of the elements in the table below is a positive ion with a charge of one?