92. Round the answer for each problem to the correct num-ber of significant figures.a. (7.31 ×10 4) +(3.23 ×10 3)b. (8.54 ×10 -3) -(3.41 ×10 -4)c. 4.35 dm ×2.34 dm ×7.35 dmd. 4.78 cm +3.218 cm +5.82 cme. 38,736 km ÷4784 km93. The accepted length of a steel pipe is 5.5 m. Calculate the percent error for each of these measurements.94. The accepted density for copper is 8.96 g/mL. Calculate the percent error for each of these measurements.Section 2.4Mastering Concepts95. Heating FuelsWhich type of graph would you use to depict how many households heat with gas, oil, or electricity? Explain.96. Gasoline ConsumptionWhich type of graph would you choose to depict gasoline consumption over a 10-year period? Explain.97. How can you find the slope of a line graph?Mastering Problems12.010.08.06.04.02.00Density (cm3)MaterialsWoodWaterSugarGlassIronLeadMercuryDensity Comparison■Figure 2.1998. Use Figure 2.19to answer the following questions.a. Which substance has the greatest density?b. Which substance has the least density?c. Which substance has a density of 7.87 g/cm 3?d. Which substance has a density of 11.4 g/cm 3?Chapter 2 • Assessment 63

Chapter Test glencoe.comMixed Review99. a. 1.31 ×10 4cm 2b. 2.73 ×10 6m 2c. 9.26 ×10 -8m 2d. 3.1 ×10 2e. 2.2 ×10 −5f. 2.00 ×10 1100. a. 301 cg101. density =6.82 g/mL% error =1.87%102. No, the conversion is not correct because the units of rate should be m/min. This expression yields the units m h/min 2. The last conversion factor should be 60 min/1 h.103. volume =29 mL104. mass =445.20 gdensity =7.15 g/mL105. 12.5 g lead106. The third student (2.87 cm) is correct. A meterstick has markings to the millimeter, so a third digit should be estimated.107. density black hole=4.5273 ×10 10g/cm 3108. The density of the black hole is 4.5273 ×10 10g/cm 3(almost fifty billion) times greater than that of water.109. 3.72 m determines the number of significant figures in the answer because it is the original value having the fewest number of significant figures.110. a. 0.00321 gb. 3.88 kgc. 219,000 md. 25.4e. 0.0876 cmf. 0.00311 mg111. slope =2.7 g/mL112. 0.24 g dextromethorphan/bottle113. Extrapolation of measured data extends the line to this point. The graph shows that an object with no mass will have no volume.114. 8.1956 m, because it has the greatest number of significant figures.115. Equal place values should be added to each other.116. Answers will vary but might include that units based on powers of ten are easy to convert from one to another. Most disadvantages involve the initial changing from another system to SI.117. There is no chance for matter to interfere with the speed measurement in a vacuum.Think CriticallyMixed Review

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