Introduction to Chemistry

Introduction to chemistry Multiple Choice 1. Which SI prefix means 1000? A. Milli B. Centi C. Deci D. Kilo Answer: D; Difficulty: easy; Reference: Section 2.5 2. The number, 14.74999, when rounded to three digits is A. 15.0 B. 14.8 C. 14.7 D. 10.0 Answer: C; Difficulty: easy; Reference: Section 2.3 3. How many significant figures are in the number 14.38? A. 1 B. 2 C. 3 D. 4 Answer: D; Difficulty: easy; Reference: Section 2.3 4. How many significant figures are in the number 1.500? A. 1 B. 2 C. 3 D. 4 Answer: D; Difficulty: easy; Reference: Section 2.3 5. How many significant figures are in the number 14.04? A. 1 B. 2 C. 3 D. 4 Answer: D; Difficulty: easy; Reference: Section 2.3 6. How many significant figures are in the number 1360? A. 1 B. 2 C. 3 D. 4 Answer: C; Difficulty: easy; Reference: Section 2.3 7. How many significant figures are in the number 0.005? A. 1 B. 2 C. 3 D. 4 Answer: A; Difficulty: easy; Reference: Section 2.3 8. How many significant digits are in the number 1.30 X 104? A. 1 B. 2 C. 3 D. 4 Answer: C; Difficulty: easy; Reference: Section 2.3 9. The density of a solid is 1.36g/mL. The specific gravity of the substance is A. 1.00 B. 1.40 C. 1.36 D. Cannot be determined Answer: C; Difficulty: easy; Reference: Section 2.9 10. One kilometer is equal to A. 0.001m B. 0.01m C. 100m D. 1000m Answer: D; Difficulty: easy; Reference: Section 2.5 11. One centigram is equal to A. 0.001g B. 0.01g C. 100g D. 1000g Answer: B; Difficulty: easy; Reference: Section 2.5 12. One millimeter is equal to A 0.001m B. 0.01m C. 100m D. 1000m Answer: A; Difficulty: easy; Reference: Section 2.5 13. The temperature of 400. degrees Celsius is equal to A. 127 K B. 163 K C. 637 K D. 673 K Answer: D; Difficulty: easy; Reference: Section 2.8 14. The temperature of -100. degrees Celsius is equal to A. -173 K B. -137 K C. 137 K D. 173 K Answer: D; Difficulty: easy; Reference: Section 2.8 15. A temperature of 100 K is equal to which Celsius temperature? A. -173 B. -137 C. 237 D. 273 Answer: A; Difficulty: easy; Reference: Section 2.8 16. The temperature of 40.0 degrees Fahrenheit is equal to which Celsius temperature? A. 4.44 B. 20.0 C. 45.0 D. 115 Answer: A; Difficulty: medium; Reference: Section 2.8 17. The temperature of 40.0 degrees Celsius is equal to which Fahrenheit temperature? A. 23.0 B. 13.0 C. 74.0 D. 104 Answer: D; Difficulty: medium; Reference: Section 2.8 18. When the Celsius temperature changes 40. degrees, the Kelvin temperature will change A. 40 degrees B. 277 degrees C. 313 degrees D. 72 degrees Answer: A; Difficulty: easy; Reference: Section 2.8 19. A piece of metal has a mass of 86.24g and a volume of 13.4mL. What is its density? A. 0.155g/mL B. 6.44g/mL C. 72.8g/mL D. 99.6g/mL Answer: B; Difficulty: easy; Reference: Section 2.9 20. A liquid has a mass of 40.24g and a volume of 50.0mL. What is its density? A. 0.805g/mL B. 1.24g/mL C. 9.76g/mL D. 90.2g/mL Answer: A; Difficulty: easy; Reference: Section 2.9 21. A solid substance has a density of 4.36g/mL. What is the volume of 30.0g of this substance? A. 0.145mL B. 6.88mL C. 34.36mL D. 131mL Answer: B; Difficulty: medium; Reference: Section 2.9 22. A liquid has a density of 1.27g/mL. What is the mass of 20.0mL of this liquid? A. 0.0635g B. 15.7g C. 21.27g D. 25.4g Answer: D; Difficulty: medium; Reference: Section 2.9 23. Convert 3.00 yards into centimeters. A. 22.9cm B. 43.2cm C. 254cm D. 274cm Answer: D; Difficulty: easy; Reference: Section 2.6 24. Convert 3.00 feet into centimeters. A. 10.2cm B. 14.2cm C. 25.4cm D. 91.4cm Answer: D; Difficulty: medium; Reference: Section 2.6 25. Convert 3.00 inches into centimeters. A. 1.18cm B. 2.54cm C. 7.62cm D. 10.2cm Answer: C; Difficulty: easy; Reference: Section 2.6 26. Convert 3.00 centimeters into inches. A. 1.18 inches B. 2.54 inches C. 7.62 inches D. 10.2 inches Answer: A; Difficulty: easy; Reference: Section 2.6 27. Which SI unit is most appropriate to measure the distance between Chicago and Detroit? A. Millimeter B. Centimeter C. Meter D. Kilometer Answer: D; Difficulty: medium; Reference: Section 2.5 28. Which SI unit is most appropriate to measure the thickness of a dime? A. Meter B. Millimeter C. Decimeter D. Kilometer Answer: B; Difficulty: medium; Reference: Section 2.5 29. Multiply (40.36) by (37.4). The product expressed to the proper number of significant figures is A. 151 B. 1509 C. 1510 D. 1509.464 Answer: C; Difficulty: easy; Reference: Section 2.4 30. Divide 1436 by 203. The quotient expressed to the proper number of significant figures is A. 0.141 B. 0.1414 C. 7.07 D. 7.074 Answer: C; Difficulty: easy; Reference: Section 2.4 31. Add 114.32 + 12.1 + 13. The sum expressed to the proper number of significant figures is A. 139 B. 139.4 C. 139.42 D. 140 Answer: A; Difficulty: easy; Reference: Section 2.4 32. Subtract 14.3 from 130.670. The difference expressed to the correct number of significant figures is A. 116 B. 116.3 C. 116.4 D. 116.37 Answer: C; Difficulty: easy; Reference: Section 2.4 33. How many significant figures should be included in the answer to the following calculation? (3.48) (3.6) / 2.470 A. 1 B. 2 C. 3 D. 4 Answer: B; Difficulty: easy; Reference: Section 2.4 34. How many significant figures should be included in the answer to the following calculation? (3.60) (2.489) (5.1110) A. 2 B. 3 C. 4 D. 5 Answer: B; Difficulty: easy; Reference: Section 2.4 35. How many significant figures should be included in the answer to the following calculation? (3.4876) / (4.11) A. 2 B. 3 C. 4 D. 5 Answer: B; Difficulty: easy; Reference: Section 2.4 36. How many zeroes are significant in the number 0.0040? A. 1 B. 2 C. 3 D. 4 Answer: A; Difficulty: medium; Reference: Section 2.3 37. How many zeroes are significant in the number 0.03003? A. 1 B. 2 C. 3 D. 4 Answer: B; Difficulty: medium; Reference: Section 2.3 38. How many zeroes are significant in the number 40400302? A. 1 B. 2 C. 3 D. 4 Answer: D; Difficulty: medium; Reference: Section 2.3 39. How many zeroes are significant in the number 30000.? A. 1 B. 2 C. 3 D. 4 Answer: D; Difficulty: medium; Reference: Section 2.3 40. What number is indicated by the SI prefix milli? A. 1/100 B. 1/1000 C. 100 D. 1000 Answer: B; Difficulty: easy; Reference: Section 2.5 41. Convert 4.30 feet into centimeters. A. 10.9cm B. 30.5cm C. 131cm D. 151cm Answer: C; Difficulty: medium; Reference: Section 2.6 42. Convert 10.00 grams into decigrams. A. 1.000dg B. 10.00dg C. 100.0dg D. 1000.dg Answer: C; Difficulty: medium; Reference: Section 2.5 43. The density of copper is 8.96g/mL. The mass of 7.00mL of copper is A. 62.7g B. 1.28g C. 0.781g D. 1.96g Answer: A; Difficulty: medium; Reference: Section 2.9 44. The density of copper is 8.96g/mL. The volume of 12.0g of copper is A. 0.747g B. 1.34g C. 3.04g D. 108g Answer: B; Difficulty: medium; Reference: Section 2.9 45. The mass of a substance is 17.46g and its volume is 3.42mL. What is the density of the substance rounded to the correct number of significant figures? A. 0.1959g/mL B. 0.196g/mL C. 5.105g/mL D. 5.11g/mL Answer: D; Difficulty: medium; Reference: Section 2.3 and 2.9 46. Convert 30.0 milliliters to Liters. A. 0.0300L B. 0.00300L C. 300.L D. 30000L Answer: A; Difficulty: easy; Reference: Section 2.5 47. The space occupied by a sample is its A. Mass B. Volume C. Length D. Temperature Answer: B; Difficulty: easy; Reference: Section 2.9 48. If the Celsius temperature of a sample changes twenty degrees, how many degrees does its Kelvin temperature change? A. 20 B. 257 C. 273 D. 293 Answer: A; Difficulty: easy; Reference: Section 2.8 49. A rectangular piece of metal measures 8.0cm by 1.20m by 15.0mm. What is its volume rounded to the correct number of significant figures? A. 14cm3 B. 144cm3 C. 1400cm3 D. 1440cm3 Answer: C; Difficulty: easy; Reference: Section 2.4 50. A cube measures 13.00cm on edge. What is its volume? A. 13.00cm3 B. 169.0cm3 C. 2197cm3 D. 28600cm3 Answer: C; Difficulty: easy; Reference: Section 2.4 51. A metal cube measures 8.60cm on edge and has a density of 11.4g/cm3. What is its mass? A. 98.0g B. 843g C. 7250g D. 62400g Answer: C; Difficulty: medium; Reference: Section 2.9 52. A 48.0g piece of metal is dropped into 50.0mL of water in a graduated cylinder. The water level rises to 62.4mL. What is the density of the metal? A. 12.4mL B. 0.258mL/g C. 3.87g/mL D. 595gmL Answer: C; Difficulty: medium; Reference: Section 2.9 53. One centimeter is equal to A. 2.54 inches B. 0.394 inches C. 12.0 inches D. 0.100 inches Answer: B; Difficulty: easy; Reference: Section 2.6 54. An empty graduated cylinder has a mass of 68.00g. 50.0mL of water is added to the cylinder and its mass increases to 109.5g. What is the density of the liquid? A. 41.5g B. 1.20mL/g C. 0.830g/mL D. 1.36g/mL Answer: C; Difficulty: medium; Reference: Section 2.9 55. A car gets 25.6 miles per gallon of gasoline. A full tank of gasoline contains 56.8 liters. How many miles can this car travel on a full tank of gasoline? ( 1.000L = 1.057qt ) A. 1454 miles B. 96.9 miles C. 1.71 miles D. 384 miles Answer: D; Difficulty: medium; Reference: Section 2.6 56. Convert 4.34 yards to centimeters. A. 4.34cm B. 132cm C. 264cm D. 397cm Answer: D; Difficulty: hard; Reference: Section 2.6 57. The number of centimeters in one inch is A. 0.109 B. 0.328 C. 0.394 D. 2.54 Answer: D; Difficulty: easy; Reference: Section 2.6 58. Add: 3.604m + 104.29m + 3.1m + 17.41m. The sum expressed in the correct number of significant figures is A. 13m B. 128m C. 130m D. 128.4m Answer: D; Difficulty: easy; Reference: Section 2.4 59. Subtract: 14.278m from 106.31m. The difference expressed in the correct number of significant figures is A. 92.032m B. 92.03m C. 92.0m D. 92m Answer: B; Difficulty: easy; Reference: Section 2.4 60. Multiply: (3.687) (14.1) (36.22). The product expressed in the correct number of significant figures is A. 1882.9583 B. 188 C. 1883.0 D. 1880 Answer: D; Difficulty: easy; Reference: Section 2.4 61. Divide: 34.72 by 4.7. The quotient expressed to the correct number of significant figures is A. 0.14 B. 0.1 C. 7.39 D. 7.4 Answer: D; Difficulty: easy; Reference: Section 2.4 62. Divide: 32.14 by 0.204. The quotient expressed to the correct number of significant figures is A. 157.55 B. 158 C. 6347 D. 6350 Answer: B; Difficulty: easy; Reference: Section 2.4 63. When expressed in proper scientific notation the number 4289 is A. 4.289 X 10-4 B. 4.289 X 10-3 C. 4.289 X 103 D. 4.289 X104 Answer: C; Difficulty: easy; Reference: Section 2.1 64. When expressed in proper scientific notation the number 286 is A. 2.86 X 101 B. 2.86 X 102 C. 2.86 X 10-2 D. 28.6 X 101 Answer: B; Difficulty: easy; Reference: Section 2.1 65. When expressed in proper scientific notation the number 0.00364 is A. 3.64 X 103 B. 3.64 X 102 C. 3.64 X 10-2 D. 3.64 X 10-3 Answer: D; Difficulty: easy; Reference: Section 2.1 66. When expressed in proper scientific notation the number 0.000034 is A. 3.4 X 104 B. 3.4 X 10-4 C. 3.4 X 103 D. 3.4 X 10-5 Answer: D; Difficulty: easy; Reference: Section 2.1 67. Express the number 2.64 104 in decimal notation A. 0.000264 B. 0.0000264 C. 26400 D. 2640 Answer: C; Difficulty: easy; Reference: Section 2.1 68. Express the number 3.00 102 in decimal notation A. 3.00 B. 30.0 C. 300. D. 3000. Answer: C; Difficulty: easy; Reference: Section 2.1 69. Express the number 4.317 10-4 in decimal notation A. 0.04317 B. 0.004317 C. 0.0004317 D. 43170 Answer: C; Difficulty: easy; Reference: Section 2.1 70. Express the number 5.0 10-2 in decimal notation A. 500 B. 50 C. 0.050 D. 0.0050 Answer: C; Difficulty: easy; Reference: Section 2.1 71. Multiply: ( 4.36 10-2 ) ( 3.17 104 ). When expressed properly the product is A. 1.38 X 103 B. 1.38 X 102 C. 1.38 X 10-2 D. 1.38 X 105 Answer: A; Difficulty: easy; Reference: Section 2.4 72. Multiply: ( 5.24 104 ) ( 2.36 10-5 ). When expressed properly the product is A. 1.24 X 10-1 B. 1.24 X 100 C. 1.24 X 101 D. 1.24 X 109 Answer: B; Difficulty: easy; Reference: Section 2.4 73. Divide: 3.724 10-3 by 2.46 104. When expressed properly the result is A. 1.51 X 101 B. 1.51 X 10-7 C. 6.61 X 101 D. 6.61 X 102 Answer: B; Difficulty: easy; Reference: Section 2.4 74. Divide: 4.863 104 by 2.12 104. When expressed properly the result is A. 4.36 X 10-1 B. 4.36 X 108 C. 2.29 X 108 D. 2.29 X 100 Answer: D; Difficulty: easy; Reference: Section 2.4 Perform the following set of operations and choose the alternative that expresses the result to the proper number of significant figures. 1.80 x 10–4 1.804 x 104 1.80 x 104 1.8 x 104 Answer: C; Difficulty: hard; Reference: Section 2.4 Perform the following set of operations and choose the alternative that expresses the result to the proper number of significant figures. 6.0 6.03 6.034 6 Answer: A; Difficulty: hard; Reference: Section 2.4 Perform the following set of operations and choose the alternative that expresses the result to the proper number of significant figures. 65.94 65 70 65.9 Answer: D; Difficulty: hard; Reference: Section 2.4 Convert 12.5 m3 to cm3. 1.25 x 103 cm3 1.25 x 107 cm3 1.25 x 105 cm3 1.25 x 10–3 cm3 Answer: B; Difficulty: hard; Reference: Section 2.6 Convert 76.9 L to cm3. 76900 cm3 7690 cm3 76900000 cm3 769000 cm3 Answer: A; Difficulty: hard; Reference: Section 2.6 Convert 33.0 inch2 to mm2. 2.13 x 103 mm2 8.38 x 102 mm2 2.13 x 104 mm2 5.12 x 102 mm2 Answer: C; Difficulty: hard; Reference: Section 2.6 An empty jar weighs 1.43 pounds. How much will it weigh when 1.00 L of homogenized milk is poured into it? The density of homogenized milk is 1.03 g/mL. (1 pound = 453.6 g) 442 pounds 3.57 pounds 2.46 pounds 3.70 pounds Answer: D; Difficulty: hard; Reference: Section 2.9 An empty glass tube weighs 37.3 g. When filled to the rim with water, it weighs 54.1 g. What is the volume of the glass tube? 16.8 cm3 54.1 cm3 37.3 cm3 91.4 cm3 Answer: A; Difficulty: hard; Reference: Section 2.9 How many grams of iron (density = 7.87 g/mL ) would occupy the same volume as 96.4 g of aluminum (density = 2.70 g/mL)? 4.54 g 33.1 g 281 g 220. g Answer: C; Difficulty: hard; Reference: Section 2.9 If you travel to Canada, speed limits are posted in km/hr. For a speed limit of 70. mi/hr, what would be the speed limit posted on a Canadian highway? (1 mile = 1.609 km) 110 km/hr 44 km/hr 68 km/hr 72 km/hr Answer: A; Difficulty: hard; Reference: Section 2.6 A police car on a high-speed chase travels at a speed of 85 mi/hr. The chase covered 82.3 miles of roadway. For how long were the police chasing the suspects? 63 minutes 58 minutes 291 minutes 97 minutes Answer: B; Difficulty: easy; Reference: Section 2.6 The speed of light is 2.9987 x 108 m/s. Convert this speed to km/hr. 1.0795 x 109 km/hr 1.7992 x 107 km/hr 8.3297 x 101 km/hr 8.3297 x 104 km/hr Answer: A; Difficulty: hard; Reference: Section 2.6 Calculate the density (in g/mL) of an unknown substance if 0.897 pounds occupy 13.5 inch3. 1.84 g/mL 11.9 g/mL 2.29 g/mL 1.09 g/mL Answer: A; Difficulty: hard; Reference: Section 2.9 The following alternatives represent numbers that were expressed to three significant figures. Which of the alternatives is expressed incorrectly? 45.7899 to 45.8 890.332 to 891 0.002346 to 0.00235 1543456 to 1.54 x 106 Answer: B; Difficulty: medium; Reference: Section 2.4 True/False 89. The mass of a substance depends on gravity. Answer: False; Difficulty: easy; Reference: Section 2.7 90. The weight of a substance depends on gravity. Answer: True; Difficulty: easy; Reference: Section 2.7 91. A solid with a lower density will float on a liquid with a higher density. Answer: True; Difficulty: easy; Reference: Section 2.9 92. If two substances have the same mass, the one with the greater volume will have the greater density. Answer: False; Difficulty: hard; Reference: Section 2.9 93. The prefix kilo means 1000. Answer: True; Difficulty: easy; Reference: Section 2.5 94. A solid with a specific gravity of 0.800 will float in water. Answer: True; Difficulty: medium; Reference: Section 2.9 95. The meter is a unit of length. Answer: True; Difficulty: easy; Reference: Section 2.7 96. The mass of a substance is independent of its location. Answer: True; Difficulty: easy; Reference: Section 2.7 97. The density of liquid A is 2.14g/mL and the density of liquid B is 1.46g/mL. When equal masses of these liquids are compared, liquid A will have the greater volume. Answer: False; Difficulty: hard; Reference: Section 2.9 98. A volume of 300.mL is the same as a volume of 30.0cm3. Answer: False; Difficulty: easy; Reference: Section 2.6 Two substances A and B occupy the same volume. The mass of substance A is half that of substance B. Therefore, the density of substance A is lower than the density of substance B. Answer: True; Difficulty: hard; Reference: Section 2.9 Two substances A and B have the same mass. Substance A occupies half the volume of substance B. Therefore, the density of substance A is lower than the density of substance B. Answer: False; Difficulty: hard; Reference: Section 2.9 The significant figures in a number include all the digits that are certain plus the first uncertain digit. Answer: True; Difficulty: easy; Reference: Section 2.3 The kilogram is the SI unit for mass. Answer: True; Difficulty: easy; Reference: Section 2.7 Free Response 103. A student determines the density of a solid by weighing it and then immersing it in 50.0mL of water in a graduated cylinder. The following data is obtained: Weight 39.364g Volume of water and solid 58.0mL Answer the following based on the preceding information. Answers should have units and be rounded to the proper number of significant figures. A. What is the volume of the solid? B. What is the density of the solid? C. What is the specific gravity of the solid? D. Will the solid float or sink in water? Answer: A. The volume of the solid is 8.0 mL; B. The density of the solid is 4.9g/mL; C. The specific gravity of the solid is 4.9; D. The solid will sink in water; Difficulty: easy; Reference: Section 2.9 104. A student determines the density of a liquid by weighing an empty graduated cylinder, adding 50.0mL of liquid to the cylinder and weighing the cylinder and liquid. The following data is obtained: Weight of the empty cylinder 63.416g Weight of the cylinder and liquid 104.312g Answer the following based on the preceding information. Answers should have units and be rounded to the proper number of significant figures. A. What is the mass of the liquid? B. What is the density of the liquid? C. What is the specific gravity of the liquid? D. Will the liquid float or sink in water? Answer: A. The mass of the liquid is 40.90g; B. The density of the liquid is 0.818g/mL; C. The specific gravity of the liquid is 0.818; D. The liquid will float on water; Difficulty: easy; Reference: Section 2.9 105. A. What is the difference between mass and weight? B. Which property, mass or weight, is better to use in science to describe a substance? Why is this true? C. What instruments are used to measure mass and weight? Answer: Mass is the amount of matter present in an object. Weight is a measure of the earth’s gravitational attraction on an object; B. It is better to use mass to describe a substance. Mass is better to use because it does not vary in different gravitational fields. Weight varies as the force of gravity changes; C. Mass is measured with a balance. Weight is measured with a scale; Difficulty: medium; Reference: Section 2.7 106. The density of ethanol is 0.7893g/mL. What is the mass of one pint of ethanol? Answer: The mass of one pint of ethanol is 373.4g; Difficulty: hard; Reference: Section 2.9 107. A rectangular solid has a mass of 1.490 kilograms. The solid measures 4.3cm by 10.6cm by 13.6cm. Calculate the density of the solid and express it to the correct number of significant figures in g/cm3. Answer: The density of the solid is 2.4g/cm3.; Difficulty: medium; Reference: Section 2.9 108. Of these three: four degrees Fahrenheit, four degrees Kelvin, and minus four degrees Celsius, which is the warmest? Answer: The warmest temperature is minus four degrees Celsius; Difficulty: medium; Reference: Section 2.8 109. What is the appropriate SI unit to express each of the following properties? A. The surface area of a gymnasium floor. B. The volume of air in a dining room. C. The thickness of a quarter. D. The volume of liquid in a wine bottle. E. The height of a redwood tree. F. The heat energy in a thermos of hot coffee. G. The mass of a large textbook. Answer: A. Square meters; B. Cubic meters; C. Millimeters; D. Milliliters or cubic centimeters; E. Meters; F. Kilojoules; G. Kilograms; Difficulty: medium; Reference: Section 2.5 110. Explain how an ocean of water and a cup of the same ocean water can have the same temperature but contain different amounts of heat. Answer: Temperature is the average kinetic energy of the molecules in a sample. If both samples have the same temperature they consist of molecules with the same average kinetic energy. The sample with more molecules, the ocean, must have the greater total amount of energy; Difficulty: hard; Reference: Section 2.8 Chapter 2: Atoms, Ions, and the Periodic Table 1. Which of the following were the elements according to the early Greeks? A) earth, wind, and fire D) sun, sand, and water B) earth, air, fire, and water E) none of these C) carbon, hydrogen, and oxygen Ans:  B 2. Which of the following statements regarding atoms and atomic theory is incorrect? A) “Atomos” is a Greek word meaning unbreakable. B) Democritus, a Greek philosopher, believed that matter could be broken down into infinitely small pieces. C) The ancient Greeks believed that all matter is made of four elements: earth, air, fire, and water. D) An element is a substance that cannot be broken down into simpler substances. E) By the 1700s, all chemists believed that elements were made of atoms. Ans:  E 3. Which of the following statements regarding atoms and atomic theory is incorrect? A) Antoine Lavoisier discovered in the late 1700s that matter is not gained or lost in a chemical reaction. B) Joseph Proust showed that when elements combine to form new substances, they do so in specific mass ratios. C) According to the law of multiple proportions, when water forms, the mass ratio of hydrogen to oxygen is variable. D) John Dalton's atomic theory disagreed with the ancient Greek philosophers' ideas about matter. E) The Greek philosophers did not conduct experiments to support their ideas. Ans:  C 4. The figure shows a molecular-level diagram of the chemical reaction between hydrogen and nitrogen to form ammonia. What is wrong with this diagram? A) The products contain more nitrogen atoms than the reactants. B) The products contain more hydrogen atoms than the reactants. C) The number of reactant molecules should equal the number of product molecules. D) The products should contain some unreacted hydrogen. E) The product ammonia molecules should have only two hydrogen atoms attached to nitrogen. Ans:  B 5. Which of the following elements is not one of the three most abundant elements in the human body? A) carbon B) oxygen C) iron D) hydrogen Ans:  C 6. Which of the following statements is incorrect? A) The human body is made up of about 99% carbon, hydrogen, and oxygen. B) Essential minerals come from the foods we eat and drink. C) Most of the essential minerals in our diet are classified as metals on the periodic table. D) Minerals are necessary for the growth and production of bones, teeth, blood, etc. E) Magnesium is a building-block for hemoglobin, which carries oxygen in our blood. Ans:  E 7. Which of the following observations does not relate specifically to the law of definite proportions? A) Pure water is composed of the elements oxygen and hydrogen in a mass ratio of 8 to 1. B) Any sample of a given compound always contains the same proportions by mass of the component elements. C) The mass of the products of a chemical reaction is equal to the mass of the starting materials of the reaction. D) When a metal reacts with oxygen, the oxygen content of the products is fixed at one or two values. E) When water is broken down into its elements by electrolysis, elemental oxygen and hydrogen are formed in an 8 to 1 mass ratio. Ans:  C 8. Which of the following is not part of Dalton's atomic theory? A) All matter is composed of small indivisible particles called atoms. B) All atoms of a given element have identical mass and chemical properties. C) Atoms of one element can be changed to atoms of another element in a chemical reaction. D) Atoms combine in whole-number ratios to form chemical compounds. E) Chemical reactions involve a rearrangement of the atoms in the starting materials. Ans:  C 9. Which of the following statements regarding atomic theory is incorrect? A) John Dalton's experimental results led to the law of conservation of mass. B) Antoine Lavoisier's experiments showed that the mass of the products of a chemical reaction equals the mass of the reacting substances. C) When wood is burned, the ashes weigh less than the original wood, but this is not a violation of the law of conservation of matter. D) Dalton's atomic theory says that a chemical reaction is a rearrangement of atoms into one or more different chemical substances. E) Joseph Proust's findings regarding the reactions between metals and oxygen led to the law of definite proportions. Ans:  A 10. Dalton's atomic theory consisted of all the following postulates except A) Elements are composed of indivisible particles called atoms. B) Atoms of different elements have different properties. C) The volumes of gases that combine are in small whole number ratios. D) Atoms combine in fixed ratios of whole numbers when they form compounds. E) In chemical reactions, atoms are not created or destroyed. Ans:  C 11. Rutherford's scattering experiment demonstrated A) the existence of protons. B) the existence of electrons. C) the existence of neutrons. D) that most of the mass of an atom is in its nucleus. E) that the charge-to-mass ratio of an electron is constant. Ans:  D 12. For the SO3 molecule, the Law of Definite Proportions requires that the mass ratio of S to O must be A) 32:16 B) 32:32 C) 32:48 D) 16:32 E) 16:8 Ans:  C 13. The subatomic particles of interest to chemists, that make up the atom, include all of the following except the: A) proton. D) neutron. B) alpha particle. E) alpha particle and neutron. C) electron. Ans:  B 14. In any neutral atom: A) the number of electrons equals the number of protons. B) the number of electrons is less than the number of protons. C) the number of electrons is greater than the number of protons. D) the number of electrons is equal to the number of neutrons. E) the number of neutrons is always equal to the number of protons. Ans:  A 15. An atom contains A) as many neutrons as electrons. D) as many electrons as protons. B) as many protons as neutrons. E) no protons. C) as many nuclei as electrons. Ans:  D 16. Which of the following statements regarding the nucleus of the atom is incorrect? A) The nucleus is the central core of the atom. B) The nucleus contains the electrons and the protons. C) The nucleus contains most of the mass of the atom. D) The nucleus contains the neutrons. E) The nucleus contains the neutrons and protons and most of the mass of the atom. Ans:  B 17. Which particles are found in the atomic nucleus? A) Protons and electrons D) Only electrons B) Electrons and neutrons E) Only neutrons C) Protons and neutrons Ans:  C 18. The number of ________ determines the identity of an element. A) electrons D) neutrons plus protons B) protons E) protons plus electrons C) neutrons Ans:  B 19. The atomic number of an element represents A) the number of electrons its atom can gain. B) the number of neutrons in an atom of the element. C) the number of protons in an atom of the element. D) the number of protons and neutrons in an atom of the element. E) the mass of an atom of the element. Ans:  C 20. The mass number of an atom represents A) the number of electrons in that atom. B) the number of isotopes of that atom. C) the number of neutrons in that atom. D) the number of protons in that atom. E) the number of protons and neutrons in that atom. Ans:  E 21. Which of the following is the same for isotopes of an element? A) mass number B) mass of an atom C) neutron number D) atomic number E) both atomic number and neutron number Ans:  D 22. Which of the following statements about isotopes is incorrect? A) The isotopes of an element have the same number of protons, but different numbers of neutrons. B) 1H, 2H, and 3H are all isotopes of hydrogen. C) Isotopes of an element have similar chemical properties. D) The melting point and boiling point of different isotopes of the same element will vary greatly. E) The different isotopes of an element have different mass numbers. Ans:  D 23. What do the following have in common? 17Cl–, 18Ar, and 19K+ A) Number of protons D) Number of electrons B) Number of neutrons E) They are all ions. C) They are isotopes. Ans:  D 24. Atoms of different isotopes of a given element have the same A) number of electrons. B) sum of the number of protons and neutrons. C) sum of the number of electrons and neutrons. D) sum of the number of electrons, protons, and neutrons. E) mass numbers. Ans:  A 25. The element magnesium, Mg, has three common isotopes: 24Mg, 25Mg, and 26Mg. The difference between these three isotopes is A) the number of neutrons. D) the number of protons and electrons. B) the number of electrons. E) their physical state. C) the number of protons. Ans:  A 26. The correct isotope symbol for the isotope in the figure is: A) B) C) D) E) Ans:  C 27. The correct isotope symbol for the isotope in the figure is: A) B) C) D) E) Ans:  B 28. The number of neutrons in an atom of I-131 is: A) 131 B) 78 C) 53 D) 77 E) insufficient information given Ans:  B 29. The number of neutrons in an atom of copper-65 is: A) 65 B) 29 C) 84 D) 36 E) insufficient information given Ans:  D 30. The number of neutrons in an atom of uranium-235 is: A) 235 B) 92 C) 327 D) 143 E) insufficient information given Ans:  D 31. The number of protons and neutrons in an atom of bromine-81 is: A) 81 protons and 35 neutrons. C) 46 protons and 35 neutrons. B) 35 protons and 81 neutrons. D) 35 protons and 46 neutrons. Ans:  D 32. The number of protons and neutrons in an atom of argon-38 is: A) 38 protons and 18 neutrons. D) 38 protons and 56 neutrons. B) 18 protons and 20 neutrons. E) 18 protons and 56 neutrons. C) 18 protons and 38 neutrons. Ans:  B 33. The number of protons and neutrons in an atom of magnesium-25 is: A) 25 protons and 12 neutrons. D) 12 protons and 13 neutrons. B) 12 protons and 25 neutrons. E) 13 protons and 12 neutrons. C) 25 protons and 37 neutrons. Ans:  D 34. Identify the element or ion shown in the figure. A) 18Ne2+ B) 18O C) 18Ar D) 10O2? E) 16O Ans:  B 35. The overall charge of an atom is ________ if the number of electrons is ________ than the number of protons. A) negative, less B) negative, greater C) positive, greater D) neutral, less Ans:  B 36. The overall charge of an atom is ________ if the number of electrons is ________ than the number of protons. A) negative, less B) positive, greater C) positive, less D) neutral, less Ans:  C 37. List the number of protons, neutrons, and electrons for 40Ca2+: A) 40 protons, 20 neutrons, and 20 electrons B) 40 protons, 20 neutrons, and 18 electrons C) 20 protons, 20 neutrons, and 18 electrons D) 20 protons, 20 neutrons, and 22 electrons E) 60 protons, 20 neutrons, and 18 electrons Ans:  C 38. List the number of protons, neutrons, and electrons for 35Cl: A) 35 protons, 18 neutrons, and 18 electrons B) 18 protons, 17 neutrons, and 17 electrons C) 17 protons, 18 neutrons, and 18 electrons D) 17 protons, 18 neutrons, and 17 electrons E) 52 protons, 18 neutrons, and 18 electrons Ans:  C 39. List the number of protons, neutrons, and electrons for 37Cl?: A) 37 protons, 19 neutrons, and 18 electrons B) 20 protons, 17 neutrons, and 17 electrons C) 17 protons, 20 neutrons, and 18 electrons D) 17 protons, 18 neutrons, and 20 electrons E) 54 protons, 17 neutrons, and 18 electrons Ans:  C 40. Which one of the following has as many electrons as it has neutrons? A) 1H B) 40Ca2+ C) 12C D) 19F E) 14C4– Ans:  C 41. Which one of the following has more neutrons than protons? A) 38Ca B) 15O C) 19F D) 36Ar E) 12N Ans:  C 42. Which of the following contains 18 neutrons? A) 31P B) 34S2– C) 36Cl D) 80Br– E) 18O Ans:  B 43. How many protons, neutrons, and electrons are in an atom of 197Au, the most common isotope of gold? A) 197, 79, 118 D) 79, 118, 118 B) 118, 79, 79 E) 79, 118, 79 C) 79, 197, 79 Ans:  E 44. The isotope symbol for an ion that has 13 protons, 14 neutrons, and 10 electrons is: A) B) C) D) E) none of these Ans:  D 45. The isotope symbol for an ion that has 11 protons, 12 neutrons, and 10 electrons is: A) B) C) D) E) Ans:  C 46. The isotope symbol for an ion that has 12 protons, 12 neutrons, and 10 electrons is: A) B) C) D) E) none of these Ans:  C 47. Which of the following statements regarding relative atomic masses is incorrect? A) Relative atomic mass is one of the numbers that appears on a typical periodic table. B) The average mass of the individual isotopes of an element considering the natural abundance of each is the relative atomic mass of that element. C) The relative atomic mass of carbon is 12.01 amu because carbon-12 is the most abundant isotope, with smaller amounts of carbon-13 and carbon-14. D) The terms “mass number” and “relative atomic mass” can be used interchangeably. E) Mass spectrometry is used to find the mass of each isotope of an element, and measure their abundance. Ans:  D 48. On the planet Melmac, in a galaxy far, far away, argon has three naturally occurring isotopes as follows: Isotope Mass (amu) Natural Abundance (%) Argon-40 39.962 74.20 Argon-38 37.963 15.15 Argon-36 35.968 10.65 What is the relative atomic mass of argon on Melmac? A) 39.23 amu B) 39.96 amu C) 37.96 amu D) 35.97 amu E) 40.00 amu Ans:  A 49. On the planet Invertios, boron has two isotopes as follows: Isotope Mass (amu) Natural Abundance (%) Boron-10 10.0129 80.00 Boron-11 11.0093 20.00 Estimate the relative atomic mass of boron on Invertios. A) 10.0 amu B) 10.2 amu C) 10.5 amu D) 10.8 amu E) 11.0 amu Ans:  B 50. An element, El, has two isotopes with the following masses and abundances: 38El 38.012 amu 75.68% 46El 45.974 amu 24.32% What is the identity of this element? A) Ar B) K C) Ca D) S E) Cl Ans:  A 51. Naturally occurring copper consists of copper-63 (62.9296 amu), and copper-65 (64.9278 amu). Using the relative atomic mass from the periodic table, which of the following is the best estimate of the percent abundance of the two isotopes of copper? A) 50% copper-63 and 50% copper-65 D) 90% copper-63 and 10% copper-65 B) 75% copper-63 and 25% copper-65 E) 10% copper-63 and 90% copper-65 C) 25% copper-63 and 75% copper-65 Ans:  B 52. Boron has two isotopes: B-10 and B-11, with masses of 10.013 amu and 11.009 amu, respectively. The relative atomic mass of boron is 10.81 amu. Which statement best describes the percent abundance of the isotopes of boron? A) It contains more B-10 than B-11. B) It contains more B-11 than B-10. C) It contains equal amounts of B-10 and B-11. D) There must be a third isotope of boron. E) A mass spectrum of boron is necessary to answer this question. Ans:  B 53. Which of the following statements about Mendeleev's periodic table is incorrect? A) Mendeleev arranged the known elements in order of increasing relative atomic mass. B) He grouped elements with similar properties into columns and rows so that their properties varied in a regular pattern. C) He arranged the elements so that they were in increasing atomic number order. D) He was able to predict the existence and properties of several elements that were unknown at the time. E) Mendeleev developed his table before the discovery of protons. Ans:  C 54. Which of the following statements about the modern periodic table in your text is incorrect? A) The periodic table is arranged by increasing atomic mass. B) The elements are arranged in rows and columns to emphasize periodic properties. C) Elements in the same vertical column are called groups or families. D) Each group has a Roman numeral and a letter associated with it. E) A horizontal row of elements is called a period. Ans:  A 55. A horizontal row of elements in the periodic table is called a: A) group. D) both group and family are correct. B) family. E) both group and period are correct. C) period. Ans:  C 56. A vertical column in the periodic table is called a: A) family or group. B) column. C) cohort. D) period. E) covey. Ans:  A 57. Which of the following terms does not apply to the major categories of elements in the periodic table? A) metals D) metalloids B) antimetals E) both antimetals and metalloids C) nonmetals Ans:  B 58. Which of the following statements does not apply to metalloids? A) The physical properties of metalloids resemble those of a metal. B) All metalloids are electrical insulators. C) Metalloids lie along the stair-step line beginning at boron. D) The chemical properties of metalloids are similar to nonmetals. E) Metalloids are also known as semi-metals. Ans:  B 59. Which of the following does not apply to the main-group elements? A) Main-group elements are also known as representative elements. B) Main-group elements are in groups labeled with the letter A. C) Main-group elements are in groups labeled with the letter B. D) Main-group elements include metals. E) Main-group elements include nonmetals. Ans:  C 60. Sodium reacts vigorously with water to form hydrogen gas and a compound containing sodium ions. Which other element is expected to react with water in a similar way? A) hydrogen B) aluminum C) nitrogen D) potassium E) silicon Ans:  D 61. Elements in Group IA (1) (except hydrogen) are called: A) alkaline earth metals. D) nonmetals. B) alkali metals. E) halogens. C) transition metals. Ans:  B 62. Elements in Group VIIA (17) are called: A) halogens. D) inert gases. B) chalcogens. E) alkali metals. C) noble gases. Ans:  A 63. Elements in Group IIA (2) are called: A) halogens. D) alkaline earth metals. B) noble gases. E) chalcogens. C) alkali metals. Ans:  D 64. Elements in Group VIIIA (18) are called: A) halogens. D) alkaline earth metals. B) noble gases. E) chalcogens. C) alkali metals. Ans:  B 65. Which of the following statements applies to noble gases? A) Noble gases exist as diatomic molecules in their elemental form. B) Noble gases are found in Group VIIIA (18) in the periodic table. C) Noble gases are very reactive. D) Noble gases were discovered in ancient times. E) Many compounds are known for each noble gas. Ans:  B 66. Which of the following statements regarding ion formation is incorrect? A) Nonmetals usually gain electrons to form ions that have a noble gas electron count. B) Main-group metals usually lose electrons to form ions that have a noble gas electron count. C) Elements in the same group often form ions of the same charge. D) The charge of any element's ion can be simply predicted using the periodic table. E) All of these statements are correct. Ans:  D 67. What changes when an ion is formed from an atom? A) Neutrons are lost or gained. B) Protons are lost or gained. C) The nucleus disintegrates. D) Electrons are lost or gained. E) Either protons or electrons are lost or gained. Ans:  D 68. Which of the following is the most likely mass for an atom of bromine-81? A) 81.000 amu D) 81.331 amu B) 80.875 amu E) 81.500 amu C) 80.916 amu Ans:  C 69. Which of the following is the most likely mass for an atom of silver-107? A) 107.000 amu D) 106.500 amu B) 107.500 amu E) 107.100 amu C) 106.905 amu Ans:  C 70. Which of the following is the most likely mass for an atom of silver-109? A) 109.000 amu D) 108.905 amu B) 108.500 amu E) 109.100 amu C) 108.000 amu Ans:  D 71. To the correct number of significant figures, the mass of exactly 250 atoms of mercury would be: A) 200.6 amu D) 5.0100 ? 104 amu B) 250 amu E) 1.246 amu C) 5.015 ? 104 amu Ans:  C 72. To the correct number of significant figures, the mass of exactly 200 atoms of carbon is: A) 12.01 amu B) 24.02 amu C) 240.2 amu D) 2402 amu E) 16.65 amu Ans:  D 73. To the correct number of significant figures, the mass of exactly 400 atoms of magnesium is: A) 24.31 amu B) 9724 amu C) 97.24 amu D) 16.45 amu E) 0.06078 amu Ans:  B 74. When comparing 1000 amu of carbon atoms with 1000 amu of helium atoms: A) each sample has the same number of atoms. B) there are more carbon atoms than helium atoms. C) there are more helium atoms than carbon atoms. D) it is not possible to tell which sample contains more atoms. E) helium is a gas, so it is less dense than the carbon, and therefore there would be fewer atoms. Ans:  C 75. When comparing 10,000 amu of mercury atoms with 10,000 amu of iron atoms: A) each sample has the same number of atoms. B) there are more iron atoms than mercury atoms. C) there are more mercury atoms than iron atoms. D) it is not possible to tell which sample contains more atoms. E) mercury is a liquid, so it would be less dense than the iron, and therefore there would be fewer atoms. Ans:  B 76. When comparing a 10.00 g sample of iron with a 10.00 g sample of lead: A) each sample has the same number of atoms. B) there are more iron atoms than lead atoms. C) there are more lead atoms than iron atoms. D) it is not possible to tell which sample contains more atoms. E) the lead is heavier than the iron, and therefore there would be more atoms. Ans:  B 77. Which set of elements below contains, respectively, an alkali metal, a halogen, and a transition metal? A) Rb, Br, Ag B) Ca, Kr, Mn C) Sc, Ba, I D) H, F, V E) Li, S, Fe Ans:  A 78. Which set of elements below contains, respectively, an alkaline earth metal, a noble gas, and a metalloid? A) Na, Ar, Si B) Ba, O, As C) Ti, Cl, Pb D) Bi, Kr, B E) Mg, Ne, Ge Ans:  E 79. Which set of elements below contains, respectively, an alkaline earth metal, a noble gas, and a transition metal? A) Ca, Ar, Pb B) Mg, N, Cu C) Sr, He, Ni D) Na, Xe, Fe E) Li, Rn, Cr Ans:  C 80. Which of the following elements does not naturally occur as a diatomic molecule? A) oxygen B) nitrogen C) hydrogen D) neon E) bromine Ans:  D 81. Which of the following elements does not occur as a diatomic molecule? A) iodine B) fluorine C) nitrogen D) hydrogen E) carbon Ans:  E 82. Which of the following elements does not occur as a diatomic molecule? A) oxygen B) fluorine C) nitrogen D) neon E) iodine Ans:  D 83. To which class does the element chromium belong? A) representative (main-group) elements D) actinides B) transition elements E) metalloids C) lanthanides Ans:  B 84. To which class does the element uranium belong? A) representative (main-group) elements D) actinides B) transition elements E) metalloids C) lanthanides Ans:  D 85. To which class does the element calcium belong? A) representative (main-group) elements D) actinides B) transition elements E) metalloids C) lanthanides Ans:  A 86. Select the element that is an alkali metal in Period 3. A) Na B) Mg C) Al D) K E) Ca Ans:  A 87. Select the element that is a halogen in Period 5. A) Br B) Xe C) Te D) I E) N Ans:  D 88. Select the element that is an alkaline earth metal in Period 4. A) Mg B) Sr C) K D) C E) Ca Ans:  E 89. In which group of the periodic table do the elements not form ions? A) alkaline earth metals D) noble gases B) alkali metals E) chalcogens C) halogens Ans:  D 90. The ions of most main-group elements have the same number of ________ as the noble gas that is closest to them in the periodic table. A) neutrons D) protons and electrons B) protons E) neutrons and electrons C) electrons Ans:  C 91. The correct symbol for the ion formed by nitrogen is: A) N2? B) N3? C) N3+ D) N2+ E) N? Ans:  B 92. The correct symbol for the ion formed by sodium is: A) Na+ B) S2? C) Na? D) S2+ E) K+ Ans:  A 93. The correct symbol for the ion formed by potassium is: A) P3? B) P3+ C) K+ D) K? E) P2? Ans:  C 94. Calcium citrate is a compound found in some calcium supplement medications. The calcium in this compound consists of ions containing 18 electrons. What is the charge of the calcium ions? A) –2 B) –1 C) +1 D) +2 E) +3 Ans:  D 95. Calculate the relative atomic mass of speedium (a fictional element) which has three isotopes with the following masses and abundances: 45Sp 44.99 amu 30.0% 47Sp 46.99 amu 60.0% 48Sp 48.00 amu 10.0% A) 45.0 amu B) 46.5 amu C) 46.7 amu D) 47.0 amu E) 140 amu Ans:  B 96. Antoine Lavoisier's experiments showed that the mass of the products of a chemical reaction equals the mass of the reacting substances. Ans:  True 97. John Dalton's experimental results led to the law of conservation of mass. Ans:  False 98. When wood is burned, the ashes weigh less than the original wood, so this is a violation of the law of conservation of mass. Ans:  False 99. Dalton's atomic theory says that a chemical reaction is a rearrangement of atoms into one or more different chemical substances. Ans:  True 100. All of the statements in Dalton's original atomic theory are still considered to be correct today. Ans:  False 101. This figure shows a chemical reaction taking place. Ans:  True 102. An individual atom is made of smaller particles called subatomic particles. Ans:  True 103. Rutherford's alpha-scattering experiment suggested that the atom had a massive positively charged core, which he called the nucleus. Ans:  True 104. The number of neutrons in the nucleus of an atom determines its identity. Ans:  False 105. The number of protons in the nucleus of an atom is the atomic number of that atom. Ans:  True 106. In order for an atom of an element to be neutral, its number of electrons must equal its number of protons. Ans:  True 107. The mass number of an isotope is the sum of the number of protons and neutrons in its nucleus. Ans:  True 108. The properties of metal ions are the same as the properties of pure metal elements. Ans:  False 109. A cation is a positively charged ion that has fewer electrons than protons. Ans:  True 110. An anion is a positively charged ion that has more electrons than protons. Ans:  False 111. One atomic mass unit is equal to the mass of a carbon-12 atom. Ans:  False 112. The relative atomic mass of an element is the average mass of its individual isotopes, considering the relative abundance of each. Ans:  True 113. Lithium is composed of two isotopes: lithium-6 and lithium-7. Lithium-7 is the more abundant of the two isotopes. Ans:  True 114. The mass of exactly 100 carbon atoms is 12.01 amu. Ans:  False 115. The mass of exactly 1000 magnesium atoms is 2.431 ? 104 amu. Ans:  True 116. Mendeleev arranged his periodic table in order of increasing atomic number. Ans:  False 117. Mendeleev was able to predict the existence of unknown elements using his periodic table. Ans:  True 118. The modern periodic table is arranged in order of increasing atomic mass. Ans:  False 119. Elements within a vertical column of the periodic table are called a family or group. Ans:  True 120. A horizontal row of the periodic table is called a period. Ans:  True 121. A metalloid is an element that has physical properties similar to those of a metal, but chemical reactivity which more closely resembles a nonmetal. Ans:  True 122. Elements in the eight groups labeled “A” are transition elements. Ans:  False 123. Elements in group IIA (2) are called alkali metals. Ans:  False 124. There are seven elements that occur naturally as diatomic molecules. Ans:  True 125. Explain what is incorrect, if anything, about the figure shown. Ans: The reaction violates the law of conservation of mass, since there are not an equal number of hydrogen atoms in the two images. 126. Does the figure shown represent a chemical reaction, or simply a physical change, and does it obey the law of conservation of mass? Ans: The figure shows a chemical reaction which obeys the law of conservation of mass. 127. Draw a nuclear model of a helium-4 atom. Label the nucleus, protons, neutrons, and electrons, and show the appropriate number of each type of subatomic particle. Ans: 128. What is the difference between the mass number of an atom, and its mass in amu? Ans: The mass number is an integer, which is the sum of the protons and the neutrons in the atom, while the mass in amu is an actual measure of the mass of an atom, often to five or more significant figures. 129. The element fluffium (Fl) was discovered on a planet in a galaxy far, far away. Given the information below, calculate the relative atomic mass of fluffium. Isotope Mass (amu) Natural Abundance (%) 301Fl 300.991 67.45 303Fl 302.985 32.55 Ans: 301.6 amu 130. A new element, grubium (Gr), was discovered ground into a child's clothes. Given the information below, calculate the relative atomic mass of grubium. Isotope Mass (amu) Natural Abundance (%) 54Gr 53.992 26.46 56Gr 55.989 73.54 Ans: 55.46 amu 131. List several unique features of the elements in group VIIIA (18) of the periodic table. Ans: They are all gases, they don't normally combine with other elements or exist as diatomic molecules, and they do not form ions. 132. Describe how you would predict the charge on the ion that would be formed by a representative element. Ans: Representative metals will lose enough electrons to have the same number of electrons as the noble gas that comes before them in the periodic table, while nonmetals will gain a sufficient quantity of electrons to “catch up” to the noble gas that follows them in the periodic table. 133. When dry ice (solid carbon dioxide) is removed from the freezer, it will sublime, or go directly from the solid phase to the gas phase. Explain why this is not a violation of the law of conservation of mass. Ans: If you could capture the carbon dioxide gas and weigh it, the mass of the gas would be the same as the mass of the dry ice you started with. 134. Two balloons are filled to equal volumes with the same number of atoms. One balloon is filled with helium, while the other contains xenon. Without breathing in the contents of either balloon, describe how you could tell the difference between the two balloons, and why they would behave differently. Ans: The helium-filled balloon would float, since helium is less dense than air, due to its low relative atomic mass. The relative atomic mass of xenon is much greater than that of the nitrogen and oxygen that comprise air, so it would be denser than air, and therefore would not float.