CH2&3 Practice Multiple Choice

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1 CH2&3 Practice Multiple Choice 1. According to the law of multiple proportions: A) the total mass is the same after a chemical change as before the change. B) it is not possible for the same two elements to form more than one compound. C) the ratio of the masses of the elements in a compound is always the same. D) if the same two elements form two different compounds, they do so in the same ratio. E) none of these 2. Cathode rays are A) anions. B) protons. C) cations. D) positrons. E) electrons. 3. Which nuclide has the same number of protons as? A) B) C) D) E) 4. How many electrons does the ion have? A) 128 B) 126 C) 54 D) 52 E) Which of the following represents a pair of isotopes? Atomic Number Mass Number A) I II B) I 7 15 II 8 16 C) I 7 14 II 8 14 D) I II E) I II Neon has three naturally occuring isotopes. The abundance of 20 Ne is 90.48% and 22 Ne is 9.25%. What is the percent abundance of 21 Ne? A) 9.25% B) 0.27% C) 49.9% D) 33.2% E) 81.2% 7. Which of the following statements is not true about the element nickel? A) It is a metal. B) It is a transition element. C) It has chemical and physical properties most similar to strontium. D) It is in period 4. E) It is in group VIIIB (group 10). 8. In a particular mass of KAu(CN)2, there are atoms of gold. What is the total number of atoms in this sample? A) B) C) D) E) The correct name for Sn 2+ is

2 A) tin(i) ion. B) tin(ii) ion. C) tin. D) monotin ion. E) tin ion. 10. The chemical name for the model is A) dinitrogen tetroxide. B) nitrogen tetroxide. C) nitrogen oxide. D) nitric oxide. E) nitrogen trioxide 11. Which name formula pair is incorrect? A) HClO3, chloric acid B) HNO3, hydroiodic acid C) HNO2, nitrous acid D) H2CO3, carbonic acid E) HF, hydrofluoric acid 12. Which is a correct balanced chemical equation corresponding to the following description of a chemical reaction? Hydrochloric acid reacts with magnesium metal to produce aqueous magnesium chloride and hydrogen gas. A) 2HCl(aq) + Mg(s) MgCl2(aq) + 2H(g) B) 2HCl(aq) + Mg(s) MgCl2(aq) + H2(g) C) 2HCl(aq) + Mg(s) MgCl(aq) + H2(g) D) 2HCl(aq) + Mg(aq) MgCl2(s) + H2(g) E) HCl(aq) + Mg(s) MgCl(aq) + H(g) 13. The products of the combustion of acetaldehyde with oxygen are shown in the following equation: CH3CHO + O2 CO2 + H2O When properly balanced, the equation indicates that molecules of O2 are required to burn 2 molecules of CH3CHO. A) 2 B) 6 C) 4 D) 3 E) Which of the following chemical equations is not balanced? A) NH4NO3 N2O + 2H2O B) C12H22O11 12C + 11H2O C) 2NH4SCN + Ba(OH)2 8H2O 2NH3 + 10H2O + Ba(SCN)2 D) (NH4)2Cr2O7 N2O + Cr2O3 + 4H2O E) 2Mg + CO2 2MgO + C 15. The formula mass of zinc acetate dihydrate, Zn(CH3COO)2 2H2O, is A) 184 amu. B) 356 amu. C) 220. amu. D) 293 amu. E) 118 amu. 16. A g sample of an element contains atoms. What is the element symbol? A) Ag B) Pd C) Xe D) Ba E) Rh 17. An atom of an element weighs g. What is the atomic mass of this element in atomic mass units? A) 38.4 amu B) 33.8 amu C) 37.0 amu D) 35.1 amu E) 32.5 amu 18. Calculate the number of moles of bromine present in 15.0 ml of Br2(l), whose density is 3.12 g/ml. A) mol B) mol C) mol D) 3.41 mol E) mol

3 19. What is the percentage by mass of carbon in the insecticide Lindane, C6H6Cl6? A) 1.40 % B) 20.4 % C) 24.8 % D) 64.0 % E) 3.60 % 20. Analysis of a compound showed that it contained 14.4 % hydrogen atoms and 85.6 % carbon atoms by mass. What is its empirical formula? A) CH2 B) CH C) CH3 D) C2H3 E) C2H5 21. A particular compound contains, by mass, 25.5 % carbon, 40.4 % fluorine, and 34.1 % oxygen. A mol sample of this compound weighs 9.40 g. The molecular formula of this compound is A) CFO. B) C3F3O. C) C6F6O6. D) C4F4O4. E) C3F3O One step in the isolation of pure rhodium metal (Rh) is the precipitation of rhodium(iii) hydroxide from a solution containing rhodium(iii) sulfate according to the following balanced chemical equation: Rh2(SO4)3(aq) + 6NaOH(aq) 2Rh(OH)3(s) + 3Na2SO4(aq) If 1.80 g of rhodium(iii) sulfate reacts with excess sodium hydroxide, what mass of rhodium(iii) hydroxide may be produced? A) 1.12 g B) 3.60 g C) 2.24 g D) 1.80 g E) g 23. SO2 reacts with H2S as follows: 2H2S + SO2 3S + 2H2O When 7.50 g of H2S reacts with g of SO2, which statement applies? A) 6.38 g of sulfur is formed. B) SO2 is the limiting reagent. C) mol of H2S remains. D) 10.6 g of sulfur is formed. E) 1.13 g of H2S remains. 24. A 5.95-g sample of AgNO3 is reacted with BaCl2 according to the equation 2AgNO3(aq) + BaCl2(aq) 2AgCl(s) + Ba(NO3)2(aq) to give 3.92 g of AgCl. What is the percent yield of AgCl? A) 52.1 % B) 100 % C) 65.9 % D) 78.1 % E) 39.0 %

4 CH2&3 Practice Multiple Choice Answer Section 1. ANS: E PTS: 1 DIF: moderate REF: 2.1 OBJ: Explain the significance of the law of multiple proportions. TOP: general concepts matter KEY: compound 2. ANS: E PTS: 1 DIF: easy REF: 2.2 OBJ: Describe Thomson's experiment in which he discovered the electron. KEY: structure of the atom discovery of electron 3. ANS: E PTS: 1 DIF: easy REF: 2.3 OBJ: Write the nuclide symbol for a given nuclide. KEY: nuclear structure 4. ANS: C PTS: 1 DIF: easy REF: 2.3 OBJ: Write the nuclide symbol for a given nuclide. 5. ANS: A PTS: 1 DIF: easy REF: 2.3 OBJ: Define and provide examples of isotopes of an element. KEY: isotope 6. ANS: B PTS: 1 DIF: easy REF: 2.4 OBJ: Determine the atomic mass of an element from the isotopic masses and fractional abundances. 7. ANS: C PTS: 1 DIF: easy REF: 2.5 OBJ: Find the main-group and transition elements on the periodic table. TOP: early atomic theory periodic table 8. ANS: A PTS: 1 DIF: easy REF: 2.6 OBJ: Determine whether a chemical formula is also a molecular formula. KEY: chemical formula 9. ANS: B PTS: 1 DIF: easy REF: 2.8 OBJ: Apply the rules for naming monatomic ions. 10. ANS: A PTS: 1 DIF: easy REF: 2.8 OBJ: Name a binary molecular compound from its molecular model. (Example 2.8) KEY: nomenclature of simple compound binary molecular compound 11. ANS: B PTS: 1 DIF: easy REF: 2.8 OBJ: Learn the approach for naming binary acids and oxoacids. 12. ANS: B PTS: 1 DIF: moderate REF: 2.9 OBJ: Write chemical equations using appropriate phase labels,symbols of reactions conditions,

5 and the presence of a catalyst. TOP: early atomic theory chemical equation KEY: balancing chemical equation 13. ANS: E PTS: 1 DIF: moderate REF: 2.10 OBJ: Master techniques for balancing chemical equations. (Example 2.12) TOP: early atomic theory chemical equation KEY: balancing chemical equation 14. ANS: D PTS: 1 DIF: easy REF: 2.10 OBJ: Determine if a chemical reaction is balanced. TOP: early atomic theory chemical equation KEY: balancing chemical equation 15. ANS: C PTS: 1 DIF: easy REF: 3.1 OBJ: Calculate the formula mass from a formula. (Example 3.1) TOP: stoichiometry mass and moles of substance KEY: formula mass 16. ANS: A PTS: 1 DIF: moderate REF: 3.2 OBJ: Understand how the molar mass is related to the formula weight of a substance. TOP: stoichiometry determining chemical formulas 17. ANS: A PTS: 1 DIF: easy REF: 3.2 OBJ: Calculate the mass of atoms and molecules. (Example 3.3) TOP: stoichiometry mass and moles of substance KEY: mole mole calculations 18. ANS: C PTS: 1 DIF: moderate REF: 3.2 OBJ: Convert from grams of substance to moles of substance. (Example 3.5) TOP: stoichiometry mass and moles of substance KEY: mole mole calculations 19. ANS: C PTS: 1 DIF: easy REF: 3.3 OBJ: Calculate the percentage composition of the elements in a compound. (Example 3.7) TOP: stoichiometry determining chemical formulas 20. ANS: A PTS: 1 DIF: moderate REF: 3.5 OBJ: Determine the empirical formula of a binary compound from the masses of its elements. (Example 3.10) TOP: stoichiometry determining chemical formulas KEY: empirical formula 21. ANS: D PTS: 1 DIF: moderate REF: 3.5 OBJ: Determine the empirical formula from the percentage composition. (Example 3.11) TOP: stoichiometry determining chemical formulas KEY: molecular formula 22. ANS: A PTS: 1 DIF: easy REF: 3.7 OBJ: Relate the quantities of reactant to the quantity of product. (Example 3.13) TOP: stoichiometry stoichiometry calculation KEY: amounts of substances 23. ANS: D PTS: 1 DIF: moderate REF: 3.8 OBJ: Calculate with a limiting reactant involving masses. (Example 3.16) TOP: stoichiometry stoichiometry calculation KEY: limiting reactant 24. ANS: D PTS: 1 DIF: moderate REF: 3.8

6 OBJ: Determine the percentage yield of a chemical reaction. TOP: stoichiometry stoichiometry calculation

Practice questions for Ch. 3

Name: Class: Date: ID: A Practice questions for Ch. 3 1. A hypothetical element consists of two isotopes of masses 69.95 amu and 71.95 amu with abundances of 25.7% and 74.3%, respectively. What is the