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自然科學 大學

想問3-9的a跟c

Problems 3-1. Explain the difference between *(a) random and systematic error. (b) constant and proportional error. *(c) absolute and relative error. (d) mean and median. *3-2. Suggest two sources of systematic error and two sources of random error in measuring the length of a 3-m table with a 1-m metal rule. 3-3. Name three types of systematic errors. *3-4. Describe at least three systematic errors that might occur while weighing a solid on an analytical balance. *3-5. Describe at least three ways in which a systematic error might occur while using a pipet to transfer a known volume of liquid. 3-6. Describe how systematic method errors may be detected. *3-7. What kind of systematic errors are detected by varying the sample size? 3-8. A method of analysis yields masses of gold that are low by 0.4 mg. Calculate the percent relative error caused by this result if the mass of gold in the sample is (a) 500 mg. (b) 250 mg. V(c) 125 mg. (d) 60 mg. 3-9. The method described in Problem 3-8 is to be used for the analysis of ores that assay about 1.2% gold. What minimum sample mass should be taken if the relative érror resulting from a 0.4-mg loss is not to exceed *(a) -0.1%? (b) -0.4%? (c) -0.8%? (d) - 1.1%? 3-10. The color change of a chemical indicator requires an overtitration of 0.03 mL. Calculate the error if the total volume of titrant is percent relative (a) 50.00 mL. (c) 25.0 mL. 3-11. A loss of 0.4 mg of Zn occurs in the course of an percent relative analysis for that element. Calculate the error due to this loss if the mass of Zn in the sample is *(b) 10.0 mL. (d) 30.0 mL. 190 (c) 188 (d) 4.52 x 103 4.63 x 103 4.53 x 10 ³ √6 *(a) 30 mg. (b) 100 mg. *(c) 300 mg. (d) 500 mg. 3-12. Find the mean and median of each of the following sets of data. Determine the deviation from the mean for each data point within the sets, and find the mean devi- Vation for each set. Use a spreadsheet if it is convenient. *(a) 0.0110 0.0105 (b) 24.53 0.0104 24.68 24.81 24.77 39.61 862 (f) 850 MA 3-13. Challenge Problem: Richards and W the molar mass of lithium and colle data. 24.73 Experiment 1 2 3 4 5 6 194 447 X 10 7 448 X 107 4.58 X 10 (a) Find the mean molar t workers. (b) Find the median molar ma (c) Assuming that the cam molar mass of lithium is the absolute ertor and of the mean value demi Willard. (d) Find in the chemical ues for the molar mus since 1910, and ag a table or spreadshera 1817 given in the a Richards and Willd. Com mass versus year to la of lithium has chang Suggest possible abruptly about 18 ant de (e) The incredibly deals Richards and W that major changes will occur. Disc calculation in pat (f) What factors ha since 1910? (g) How would you mass? 6See Chapter 2 of Applications of Microsoft Excel in Analytical Chemistry, 4th ed., for information about statistical 7T. W. Richards and H. H. Willard, J. Am. Chem. Soc., 1910, 32, 4, DOI: 10.1021/ja01919a002. built-in statistical functions. "Answers are provided at the end of the book for questions and problems marked with an asterisk The I of ₂ or inc rce of able vas error c often in individu ate resul data in rtainties. dimensio andom e analysts The result

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英文 高中

想請問45 在第三段後幾句 他說並不是全部人都買單 那不就代表他不夠popular嗎 那D選項為什麼對 還有46 b跟d明明超像吧?

66 學測週計畫‧英文 x } 分。 adi) T}; 第4至7題為題組 The fair-trade movement began in Europe in the post-war period, but it didn't draw people attention until the recent 25 years. According to its fundamental principles, fair trade 2 47.) w you were in the fai making trades fair to producers by having consumers from developed countries pay slightly problem mentioned ir (A) To place more adv for end products. The primary feature of the fair-trade system that distinguishes it from that of the open marke (B) To look for more (CL To lower the fees is the requirement of minimum prices paid for goods. Moreover, during good years, an addition (D) To reduce the hi amount of money is added to encourage and profit labor-offering producers. With financial aid purchasers of fair-trade products may help producers hire more adult workers, which can reduce he hiring of child labor. By paying more, they can also guarantee the safety of workplaces, and be farmers adopt eco-friendly fertilizers to protect the environment. However, although the fair trade system seems beneficial to farmers, and trades are on the increase, it actually leaves much room for criticism. For example, getting fair trade certification is expensive for small businesses and individual producers. They have to split their hard-earne money for being a fair trade member, which ends up being a burden for the poor producers that fair trade system originally urges to help. Such high administration fees inevitably lead to the result that products are sold at much higher prices which weigh on consumers. Hence, customer base around the world is limited, because not everyone is willing to pay extra fees when they can get products of the similar quality but with lower prices. Worst of all, the administration fees don't go to the suppliers but retailers. Although there are obvious advantages of fair trade system, its disadvantages are likely to form a vicious circle and may shrink the fair trade market, if the basic problem doesn't get tackled. 44 Which of the following is the best title for this passage? (A) The History of Fair Trade qobis (Bil How to Become Fair-Trade Producers (C) How Fair Is Fair Trade? DNThe Cost of Fair-Trade Practices Which of the following statements is NOT true about fair trade? og AT of a spire- (A) Fair-trade producers use environmentally friendly fertilizers. resembles B) All fair-trade crops are sold at higher prices in the market. on its ext (C) Producers have to pay for official proof of fair-trade associations. Cam the talles Fair trade products are popular and sold to every country in the world. To dow As 46. What is the correct order of the main ideas for the paragraphs 1-3? with aw TA) Fair trade and globalization 48 Acc (B) The time when fair trade began — The advantages of fair trade → The impact of fair trade api (C) The first fair-trade producer → The increasing sales of fair-trade products A consumers to farmers (D) The goal of fair trade system → The advantages of fair trade — The imperfection of fair trade p 第責部分 第48至几題為題組 As water is to p no beautiful decorat This list could go to the similar style structures in the w One great e British architect there are mainly to break this col this innovative concept of it i building elabc functions of w Anot 2 Also calle Piano, an It purposes like two fundan rise. T Da Totein gorofa obito Bol to do 14 → The cons of fair trade → The pros of fair trade 帥8% → The help of 49. TL

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