mid1a_f03 - Avogadro's Number NA = 6.022 1023 1[7 points...

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Avogadro°s Number, N A = 6.022 × 10 23 1. [7 points] Which of the following statements is true ? (a) Air is an element (b) Air is a compound (c) Air is a heterogeneous mixture (d) Air is a homogeneous mixture (e) Air is a pure substance 2. [7 points] What is the empirical formula of the ionic compound that forms between calcium and iodine? 3. [7 points] Which of the following pairs of atoms (ions) have the same number of neutrons ? 4. [7 points] What is the empirical formula of potassium sulfite? 5. [7 points] How many carbon atoms are present in a single 2.00 ounce shot of pure ethanol (C 2 H 5 OH, density = 0.789 g/cm 3 )? [1 ounce = 29.6 mL] (a) 6.11 × 10 23 (b) 1.22 × 10 24 (c) 1.96 × 10 24 (d) 1.20 × 10 23 (e) None of the above
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6. [7 points] You are given a solid yellow crystal of unknown composition. After running a series of tests you make the following observations: (a) the crystal is an electrical insulator, (b) if you strike the crystal with a hammer it cracks in several places, (c) if you put the crystal in a beaker of water it dissolves and the resulting solution is found to be a good conductor of electricity. Which of the following substances could have properties consistent with these observations
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