1988 national - U.S. National Chemistry Olympiad: 1988...

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U.S. National Chemistry Olympiad: 1988 National Test Go to answers 1. A verbal statement or a mathematical equation that summarizes a broad variety of observations and experience is called a(n) (A) hypothesis (B) law (C) theory (D) evolution 2. The term that is related to the reproducibility or repeatability of a measurement is: (A) accuracy (B) systematic (C) precision (D) qualitative 3. A sample of carbon dioxide that undergoes a transformation from solid to liquid to gas would undergo (A) a change in mass (B) a change in density (C) a change in composition (D) no change in physical properties 4. A solution is a(n) (A) compound (B) pure substance (C) homogeneous mixture of substances (D) heterogeneous mixture of substances 5. Dalton's theory of atoms consisted of all of the following postulates except (A) elements are composed of indivisible particles called atoms. (B) atoms of different elements have different properties. (C) atoms combine in fixed ratios of whole numbers. (D) the volumes of gases consumed and produced are in ratios of small whole numbers. 6. Cathode rays are (A) a beam of positively charged particles.
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(B) nuclei of helium atoms (C) fast-moving neutrons (D) streams of electrons 7. There are two stable isotopes of carbon. They differ with respect to (A) atomic mass (B) number of protons (C) atomic number (D) electron configuration 8. One 40 Ca 2+ ion contains (A) 2 protons (B) 18 electrons (C) 21 neutrons (D) 2 electrons 9. The average atomic weight of elemental copper is reported as 63.5. Copper consists of two stable isotopes, 63 Cu and 65 Cu. Approximately what percent of naturally occurring copper is the 63 Cu isotope? (A) 30 (B) 50 (C) 70 (D) 90 10. The best molecular formula for sulfur in its naturally occurring state is (A) S (B) S 2 (C) S 6 (D) S 8 11. The correct formula for iron(III) sulfide is (A) Fe 3 S 2 (B) FeS (C) Fe 2 S 3 (D) Fe 3 S 12. What is the percentage by weight of potassium in the compound KNO 3 ? (A) 38.7 (B) 39.1 (C) 56.6
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(D) 63.1 13. If 18.5 moles of the liquid compound C 2 Cl 4 are required for a particular chemical reaction, what volume should be taken? The density of C 2 Cl 4 is 1.63 g/ml. (A) 11.3 mL (B) 30.2 mL (C) 1.88 L (D) 5.01 L 14. The principle of DuLong and Petit states that the product of the atomic weight of a solid element and its specific heat, measured at room temperature, is approximately 6.2 calories per mole per degree (25.9 Joules per mole per degree). A prospector has asked you to identify the most abundant element in a mineral sample he has found. You chemically separate the most abundant element and determine that its specific heat is 5.24 x 10¯ 2 cal per gram per degree. The element most likely is (A) Au (B) Fe (C) Ni (D) Sn 15. In the complete combustion of octane with oxygen, represented by the unbalanced chemical equation, C 8 H 18 + O 2 ----> CO 2 + H 2 O one gram of octane will yield what mass of water? (A) 0.079 g
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1988 national - U.S. National Chemistry Olympiad: 1988...

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