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210-E1-vD-SP09-ANS - Name E#3 Section II CHEM 210 Exam#1...

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Unformatted text preview: Name: % E {#3 Section: II): CHEM 210 - Exam #1 - Spring 2009 Multiple Choice (4 points each) Identifiv the choice that best answers the question and write that letter on the blank next to the number. C 1. From the results of his gold foil experiment, Ernest Rutherford concluded that: A) atoms contain roughly equal numbers of neutrons and protons. B) electrons have a charge of —1.602 x 10"9 C. C) atoms are composed of a small, dense nucleus surrounded by a cloud of electrons. D) alpha particles are helium nuclei. E) many atoms have radioactive isotopes. C. 2. An atomic mass unit (amu) is defined as A) 1/16 of the mass of one oxygen-16 atom. B) 6.022 x 1023g C) 1/12 of the mass of one carbon—12 atom. D) the mass of a single neutron E) the mass of one hydrogen-1 atom. A 3. Ethanol boils at 784°C. What is the same temperature in Kelvin? A) 351.6 K C) -194.8 K B) -351.6 K B) 194.8 K D) 173 K E 4. What is the mass number of an iron isotope with an isotopic mass of 31.974 amu ? ' A) 31 C) 15 E) 32 B) 17 D) 31.974 5 5. You have 0.250 mole of each of the following elements: Na, Mg, Ca, Ba, Br. Which sample has the largest mass? (No calculation is needed.) A) Ca B) Na C) Mg D) Br E) Ba EM 6. What is the volume ofa sample of chromium with a mass of 15.0 g? A) 108 cm3 C) 40.1 cm3 E) 15.0 cm3 B) 0.479cm3 D) 2.09 cm3 ID: D “£2; 7. How many significant figures are in the following measured value: 0.026050 A) 6 C) 4 E) 7 B) 3 D) 5 B 8. Pennies minted after 1983 are composed of 97.0 % zinc and 3.00 % copper and have a mass of 2.46 g. fi-‘— How many moles of zinc are in a post-1983 penny? A) 0.0738 mol C) 2.39 mol E) 0.0376 mol B) 0.0365 mol D) 0.00113 mol _E»2 9. Express the answer to the following expression to the correct number of significant figures: 4.8000 x it)16 60.3 +9l.l4 A) 3.2 x10” C) 3.17 x10‘4 E) 3.17 x 10'5 B) 3.170 x1014 D) 3.2 x1015 D 10. The surface area of Lake Tahoe is 495 kmz. Convert that quantity to m3. A) 4.95 x 105 m2 C) 4.95 x 10“ m2 E) 4.95 x 10“L m?- B) 0.495 m2 D) 4.95 x 108 m2 _E l 1. All atoms of the same element have the same number of in their nucleus. A) neutrons and protons D) electrons B) protons E) protons and electrons C) neutrons C. 12. What is the mass percent of nitrogen in Mg(NOz)2 ? A) 25.9 % C) 24.1 % E) 13.7 % B) 27.4% D) 12.0 % i; 13. Which of the following elements does NOT typically exist as a diatomic molecule? A) Fluorine C) Carbon E) Nitrogen B) Oxygen D) Hydrogen Chemistry 210 ' Exam 1 - SPRING 2009 Name: Kéj Section: FREE RESPONSE: Answer the following questions in the spaces provided. Show all work and express final answers with the correct number of significant figures and units to receive full credit If you use exponential notation for your answer, you must use proper scientific notation. l. (22 points) Carry out the following conversions. f N‘ A) Convert 6.0 feet (ft) to meters. [(2, 2. (l 1 points) What length (in meters) of copper wire with a diameter of 3.00 mm could be made from 20.0 moles of copper atoms. A wire is the shape of a cylinder. ' ” L 3. (15 points) Naturally occurring lithium is composed is composed of two isotopes, Lithium-7 and another isotope. Please complete the following table pertaining to these isotopes. You do NOT need to fill in the blacked-out boxes. ~ ' Isotope Symbol Isotope Mass (in the form (amu) 2X), , ._ 7‘5“"; ewe?“ Percent I Abundance Mass # Atomic # mg? #of #of Isotope Name protons neutrons 0% 3, , A: (Report to 3 decimal places.) , 1 rs - . , 7t- i _ . e .3, Lithium 7 3 g L 7.0160 :3 $7413 '2; 3 @ BMW 5”“ % Ce read? first ten Lion’s; , Later-X: == 5?.mefi ’{ooes W. k Wt A ow: : Q'gsggé e ofigzsiy ...
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