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Unformatted text preview: Exam 1 C111 Summer 2010 Name _______________________ Multiple choice , 4 points each. Circle the letter of the best response for each question. PARTIAL CREDIT MAY BE AWARDED IF SOME WORK OR COMMENT IS SHOWN. Avogadros Number N = 6.023 x 10 23 1. On a dog-sledding trip in Quebec, the temperature was - 43 o C . What is this temperature in Kelvins? a) 316 K b) 230 K c) 350 K d) 196 K 2. The density of a particular alloy of gold is 18.88 g/cm 3 . What is the volume of a block of this alloy having a mass of 0.5074 g? a) 9.58 cm 3 b) 0.104 cm 3 c) 3.72 cm 3 d) 2.69 x 10- 2 cm 3 3. Choose the answer, using the correct number of significant figures, when the following calculation is performed: (1.196 x 10- 3 )( 17.00) = ? (All of the choices are calculated correctly.) a) 0.02049944 b) 0.020499 c) 0.02050 d) 0.0205 e) 0.020 4. How many moles are there in 4.15 x 10- 2 g of lead, Pb (Z = 82)? a) 2.00 x 10- 4 mol b) 5.06 x 10- 4 mol c) 4.15 x 10- 2 mol d) 1.05 mol e) 24.1 mol 5. 0.00214 milliliters is how many microliters ( L)? a) 2.14 x 10-5 L b) 21.4 L c) 2.14 L d) 214 L 6. There are exactly 8 oz. in a cup, and exactly 2 cups in a pint. If 1.00 ounce = 29.6 mL, how many liters are there in a pint? a) 3.79 L b) 2.11 L c) 1.06 L d) 0.474 L e) 0.264 L 7. For the chemist, accuracy is best defined as: a) How close a measurement is to the "true" value. b) How close repeated measurements are to each other. c) How carefully the experiment or measurement is performed. d) When the most often obtained value is the "true" value in repeated measurements. 8. A particular chemical reaction had a theoretical yield of 0.8462 g of product. If only 0.5429 g of product were actually obtained, what is the percent yield of the reaction? a) 0.642 % b) 1.56 % c) 45.94 % d) 64.16 % e) 54.29% f) 87.53 % 9. A stream of sub-atomic particles escapes through a tiny hole in a lead box. The particle beam is passed between electrically charged plates, as illustrated. A sheet of target material shows the locations where the particles strike. Three regions of impact are observed, indicated by the letters A, B and C in the drawing. Which of the following statements best explains this observation? a) the particles had different trajectories out of the source block and strike the target randomly. (+) B b) this stream of particles consists of three kinds: one positive, one negative, and one with no charge. A c) the nucleus is very dense and occupies relatively particle beam little of the atom's volume. Particle d) the particles all have very different masses and source C travel at very different velocities. (- ) target e) protons have positive electrical charge and mass ~1 amu 10. What isotope of which element is produced by this nuclear reaction?...
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- Fall '08