c205_final_w04_04_hints

c205_final_w04_04_hints - Course CHEMISTRY Instructor P.H...

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Course: CHEMISTRY Number: 205/4 Section: 04 Instructor: P.H. Bird Examination: Alternate Date: 25th April, 2004 Time: 9:30-12:30 am # of pages: 14 Materials Allowed: A periodic table is attached to this paper - no other materials are allowed . Calculators Allowed: Yes Special Instructions: Please answer 25 questions. The first 20 are multiple choice and carry 5 marks each. The others require complete answers and are worth 10 marks each. Please read the instructions before each group of questions . Name: __________________________________ Student Number:______________ 1 2 3 4 5 6 7 8
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Chem 205 Winter 2004 Final Exam Section 04 page 2 The following 20 questions are multiple choice. You may do rough work on your exam paper, but you must mark you answers using a soft pencil on the machine readable answer form provided. Do not forget to mark your name and student number . 1. Magnesium makes up 1.3 x 10 -4 percent by mass of the elements found in a normal healthy human body. How many grams of magnesium would be found in the body of a person weighing 183 lb? (2.2 lb = 1 kg) a. 1100. g b. 0.11 g c. 11. g d. 0.24 g e. 0.10834 g Hint: You need to know the definition of percent by mass. 2. The element rhenium (Re) exists as two stable isotopes and 18 unstable ones. Which of the following represents the contents of the nucleus of 185 Re? a. 75 protons, 75 neutrons b. 75 protons, 130 neutrons c. 130 protons, 75 neutrons d. 75 protons, 110 neutrons e. 75 protons, 110 electrons Hint: You need to know how the atomic symbols are written, and specifically what that left superscript represents. 3. How many oxygen atoms are there in one formula unit of the type of of asbestos called chrysotile, Mg 3 Si 2 O 5 (OH) 4 , which is mined around Thetford Mines in Quebec? a. 10 b. 9 c. 8 d. 7 e. 6 Hint: You need to know how to “read” a chemical formula.
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Chem 205 Winter 2004 Final Exam Section 04 page 3 4. Find the error in the following pairs: a. NH 4 Br, ammonium bromide b. K 2 CO 3 , potassium carbonate c. BaPO 4 , barium phosphate d. CuCl, copper(I) chloride e. MnO 2 , manganese(IV) oxide Hint: If you assign the correct charges to each of the ions in them, one of the compounds would not have a zero total charge: which one? Of course, you need to recognize the ions. 5. Iron is biologically important for the transport of oxygen by red blood cells from the lung to various parts of the body. In the blood of an average human being, there are approximately 2.60 x 10 13 blood cells with a total of 2.90 g of iron. How many iron atoms are there in the average blood cell? (N a = 6.022 x 10 23 ) a. 8.33 x 10 -10 b. 1.20 x 10 9 c. 3.12 x 10 22 d. 2.60 x 10 13 e. 5.19 x 10 -2 Hint: Avagadro’s number, N a , is given. You need to know what it is o answer this question. 6.
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This note was uploaded on 09/01/2008 for the course CHEM 205 taught by Professor Bird during the Spring '08 term at Concordia Canada.

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c205_final_w04_04_hints - Course CHEMISTRY Instructor P.H...

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