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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

我想問一下第11題,為何D選項where不能選,the power of the place,the place ,不是地方嗎,為什麼不能用where代替. 這題答案為A(that),謝謝。

I 892009 二、綜合測驗(10%) 說明:第 11 至 20 題,每題一個空格。請依文意選出最適當的一個選項,並劃記在答案卡 。各題答對者得1分;答錯、未作答或劃記多於一個選項者, 之「選擇題答案區」 該題以零分計算。 第11至15題為題組 11 they're R one particular statue: Government buildings are often decorated with marble statues. These pieces of art give those who visit or work in these official (spaces a feeling of awe at the power of the place entering. At courthouses around the world, you'll have no trouble___ _12 Justice. Also called Lady Justice, she represents the fair justice that courts should deliver. The woman is often blindfolded and almost always carries old-fashioned balance scales. The scales show the fair way the courts will weigh evidence in a trial, and the blindfold shows how the law will is relatively not be influenced by the wealth or status of people brought to trials. However, 13 new. Lady Justice comes from the ancient Roman goddess Justitia. As her name 14, sh represented the concept of justice. Statues of this goddess showed her s a serious young woma simply carrying scales, while she was shown on coins with many different objects in her hand Not until 1543 wearing a blindfold. However, most modern statues now have this featu including the one on the US Supreme Court building. Alim to slitod a bar or vabot jud, tantoond aid diw saltos los 11. (A) that (B) how (C) what 12. (A) to spotomo) (B) spot/lissiqvi (0) (C) being spotted a) (D) where (D) spotting (A

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