practiceexam1

Practiceexam1 - p 1 1 In a given chemical compound the proportions by mass of the elements that compose it are a variable but in ratios of small

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Unformatted text preview: p. 1 1. In a given chemical compound, the proportions by mass of the elements that compose it are a. variable but in ratios of small integers. b. dependent on the origin of the compound. c. dependent on the mode of preparation of the compound. d. All of the above are correct. e. None of the above is correct. 2. A pure solid decomposes on heating, yielding a solid and a gas, each of which is a pure substance. From this we can reasonably conclude that a. the original solid is not an element. b. at least one of the products is an element. c. both products are elements. d. both (a) and (b) are true e. None of these are true 3. Which statement about balanced chemical equations is FALSE? a. The net charge of the reactants must equal the net charge of the products. b. The total mass of the reactants must equal the total mass of the products. c. The total number of atoms in the reactants must equal the total number of atoms in the products. d. The total number of moles of reactants must equal the total number of moles of products. e. Gaseous reactions for which the number of moles of reactants equals the number of moles of products are not accompanied by a change in volume if the temperature and pressure remain constant. 4. The gaseous elements H 2 and O 2 react explosively to form water (H 2 O). 3.00 L of H 2 is mixed with 2.00 L of O 2 and the mixture is ignited in a strong steel vessel. If the gas volumes are all measured at the same temperature and pressure, which gas remains unreacted, and what is its volume? a. O 2 , 0.50 L b. O 2 , 1.00 L c. H 2 , 1.00 L d. H 2 , 2.00 L e. none of these p. 2 5. Which of the following is the correct Lewis dot symbol for the S – ion? a. b. c. d. e. none of these 6. Which of the following is not isoelectronic with Ar? a. S 2– b. Cl – c. K + d. Ca 2+ e. P 2– 7. A monoatomic ion X 2+ has 25 electrons and 29 neutrons. What is the identity of element X?...
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This note was uploaded on 04/30/2008 for the course CHEM 1411 taught by Professor Parkin during the Spring '08 term at Columbia.

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Practiceexam1 - p 1 1 In a given chemical compound the proportions by mass of the elements that compose it are a variable but in ratios of small

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