C205_mid-term_w09_04-ans - _Name: _ I.D. Number: _...

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page 1 _Name: ____________________________________________ I.D. Number: ________________ CHEMISTRY 205 - SECTION 04 - MID TERM EXAM March 6 th 2009, 10:15 – 11:30 Instructor: P.H. Bird Instructions : THIS IS A CLOSED BOOK EXAM and NO MATERIALS ARE TO BE SHARED. Use the backs of the pages for rough work. Please attempt all questions. The periodic table attached is the only one you are allowed to use. No electronic dictionaries are allowed. No cell phones being as calculators are allowed. Answers : Correct choices: red , Answers or explanations: blue , Editorial Comments: green Section I. Complete each of the following five statements with the appropriate word(s). They are worth 1 mark each. 1. A mixture such as ethanol and water is called a ____ homogeneous _____ mixture. 2. Atoms of the same element which differ by the number of neutrons are called __ isotopes __. 3. A series of measurements whose average is very close to the correct value are called __ accurate __. 4. The elements in group 17 of the periodic table are know as the ____ halogens ____. 5. The acid with formula H 2 SO 3 is known as __ sulphur ous acid __. Note the formula. The formula of sulphur ic acid is given in Section III, question 3. Section II. The following 14 questions are multiple choice. They are worth 2 marks each. You may do rough work on your exam paper, but it will not be marked. You must mark your answers using a soft pencil on the machine readable answer form provided. Do not forget to mark your name and student number (your birth date is not required). 1. A pure substance that is composed of two or more different elements is a . a chemical compound. You just have to know this. b. a multi-element. c. an atom. d. a heterogeneous mixture. e. a homogeneous mixture. 2. All of the following are examples of physical properties EXCEPT a. the density of neon gas. b. the conductivity of copper wire. c. the boiling point of water. d . the frying of an egg. This involves chemical changes. It is not a physical property. e. the density of mercury metal.
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page 2 3. The radius of a helium atom is 31 pm. What is the radius in meters? a. 3.1 × 10 -14 m b. 3.1 × 10 -12 m c . 3.1 × 10 -11 m d. 3.1 × 10 -9 m e. 3.1 × 10 -8 m 1 pm is 10 -12 m. 4. J. J. Thomson determined the charge to mass ratio of electrons by a. suspending charged oil droplets between magnetic plates. That was the Millikan experiment to determine the charge on the electron.
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This note was uploaded on 11/26/2010 for the course CHEMISTRY chem205 taught by Professor Mariela during the Fall '10 term at Concordia University Irvine.

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C205_mid-term_w09_04-ans - _Name: _ I.D. Number: _...

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