Sample Questions - Chapter 2

Chemical Formulas and Composition Stoichiometry

Examples of
Multiple Choice Questions

1.: The formula weight of the compound, Al₂(SO₄)₃18H₂O is:; (a) 394.4 g; (b) 666.4 g; (c) 110,900 g; (d) 466.8 g; (e) 561.2 g
2.: The weight of a millimole of (NH₄)₂HPO₄ is:; (a) 132 g; (b) 114 g; (c) 1.14 x 10^-3 g; (d) 0.132 g; (e) 6.02 x 10²⁰ g
3.: How many moles of alanine, C₃H₇NO₂, are there in 159 g of alanine?; (a) 1.42 x 10⁴; (b) 1.78; (c) 0.992; (d) 0.560; (e) 3.31
4.: How many atoms are in one mole of CH₃OH?; (a) 6; (b) 6.0 x 10²³; (c) 12.0 x 10²³; (d) 3.6 x 10²⁴; (e) 3
5.: The mass in grams of 2.6 x 10²² chlorine atoms is:; (a) 4.4; (b) 11; (c) 0.76; (d) 1.5; (e) 3.2
6.: How many aluminum atoms are there in 3.50 grams of Al₂O₃?; (a) 4.13 x 10²²; (b) 4.90 x 10²²; (c) 2.07 x 10²²; (d) 1.68 x 10²²; (e) 2.45 x 10²²
7.: Which one of the samples contains the most atoms?; (a) 1 mol of CO₂(g); (b) 1 mol of UF₆(g); (c) 1 mol of CH₃COCH₃(l); (d) 1 mol of He(g); (e) all contain the same number of atoms
8.: Which one of the samples contains the most molecules?; (a) 1 mol of CO₂(g); (b) 1 mol of UF₆(g); (c) 1 mol of CH₃COCH₃(l); (d) 1 mol of He(g); (e) all contain the same number of molecules
9.: Which one of the samples has the largest mass?; (a) 1 mol of CO₂(g); (b) 1 mol of UF₆(g); (c) 1 mol of CH₃COCH₃(l); (d) 1 mol of He(g); (e) all have the same mass
10.: Which of the following statements is(are) FALSE?; 1. The percent by mass of each element in a compound depends on the amount of the compound.; 2. The mass of each element in a compound depends on the amount of the compound.; 3. The percent by mass of each element in a compound depends on the amount of element present in the compound.; (a) 2 and 3; (b) 1 only; (c) 1 and 2; (d) 1, 2 and 3; (e) another combination
11.: Guanidin, HNC(NH₂)₂, is a fertilizer. To three significant figures, what is the percent by mass of nitrogen in the fertilizer?; (a) 45.2%; (b) 49.4%; (c) 54.8%; (d) 65.1%; (e) 71.1%
12.: Calculate the percent, by weight, of carbon in 154 g of C₄H₈O₃?; (a) 46%; (b) 31%; (c) 72%; (d) 27%; (e) 55%
13.: Analysis of a sample of a covalent compound showed that it contained 14.4% hydrogen and 85.6% carbon by mass. What is the empirical formula for the compound?; (a) CH; (b) CH₂; (c) CH₃; (d) C₂H₃; (e) none of these
14.: An oxide of lead contains 90.65% Pb, by weight. The empirical formula is:; (a) Pb; (b) PbO; (c) Pb₃O₄; (d) Pb₂O₃; (e) PbO₂
15.: A 0.500 g sample of a compound containing only antimony and oxygen was found to contain 0.418 g of antimony and 0.082 g of oxygen. What is the simplest formula for the compound?; (a) SbO; (b) SbO₂; (c) Sb₃O₄; (d) Sb₂O₅; (e) Sb₂O₃
16.: A compound contains, by mass, 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen. A 0.320 mole sample of this compound weighs 28.8 g. The molecular formula of this compound is:; (a) C₂H₄O₂; (b) C₃H₆O₃; (c) C₂H₄O; (d) CH₂O; (e) C₄H₇O₂
17.: What mass of cerussite, PbCO₃, would contain 35.0 grams of lead?; (a) 27.1 g; (b) 45.1 g; (c) 42.4 g; (d) 35.6 g; (e) 51.7 g

Answers:

1. (b) 2. (d) 3. (b) 4. (d) 5. (d) 6. (a) 7. (c) 8. (e) 9. (b) 10. (b) 11. (e) 12. (a) 13. (b) 14. (c) 15. (e) 16. (b) 17. (b)

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