Download In-Class Exam - Fayetteville State University

Fayetteville State University
Department of Natural Sciences
CHEM 140, Summer I 2005
Friday, June 17, 2005
In-Class Exam
Note: Answer 33 questions only. Leave three questions of your choice unmarked. Mark your answers on SCANTRON provided. Each
correct answer is worth 3 points.
1.
The density of silver is 10.5 g/cm3. What would be the mass (in grams) of a piece of silver that occupies a volume of 23.6 cm 3?
A) 248 B) 0.445 C) 112 D) 2.25 E) 23.6
2.
Round the following number to two significant figures and express the result in standard exponential notation: 2296.13
A) 2.296x102 B) 2.30 x103 C) 2x103 D) 2.3x103 2.3x104
3.
1.6x102 km/hr = __________ m/s.
A) 1.6x102 B) 45 C) 16 D) 450
4.
E) 160
Which of the following is NOT a physical property of water?
A) It boils at 100 oC at 1 atm pressure B) It is a liquid at room temperature C) It freezes at O oC at 1 atm pressure
hydrogen and oxygen gas if we pass electricity through it E) It condenses at 100 oC
5.
What is the correct answer (reported to the proper number of significant figures) to the following: 6.4 x 3.23 = ______
A) 20 B) 20.67 C) 20.7 D) 20.672 E) 21
6.
The correct name for MgCl2 is ______.
A) Magnesium dichloride B) magnesium chlorate
C) manganese chloride
D) It produces
D) magnesium chloride E) magnesium chlorine
7.
Which pair of elements would you expect to exhibit the greatest similarity in their physical and chemical properties?
A) O, S B) H, He C) K, Ca D) C, N E) Si, P
8.
Which one of the following is the correct formula for ammonium sulfide?
A) (NH4)2S B) (NH4)2SO4 C) NH4SO3 D) NH3S E) N2S3
9.
The empirical formula of a compound with molecules containing 12 carbon atoms, 14 hydrogen atoms, and 6 oxygen atoms is _____.
A) C2H4O B) CHO C) C6H7O3 D) C12H14O6 E) CH2O
131 
10. There are _____ protons, _______ neutrons, and _______ electrons in 53 I .
A) 78, 53, and 72 B) 53, 131, and 52 C) 53, 78, and 54 D) 131, 53, and 54
11. The nucleus of an atom contains ______.
A) protons and neutrons B) only electrons
C) protons, neutrons, and electrons
12. The name of the binary compound N2O4 is ________.
A) oxygen nitride B) nitrogen(III) oxide C) dinitrogen tetroxide
E) 131, 53, and 52.
D) only protons
E) protons and electrons
D) nitrogen oxide
13. Which of the following compounds would you expect to be ionic?
A) SF6 B) CaO C) CO2 D) NH3
14. Isotopes are atoms that have the same number of ______ but differing number of ______.
A) neutrons, protons B) protons, electrons C) neutrons, electrons D) electrons, protons
E) protons, neutrons
15. Aluminum reacts with a certain nonmetallic element to form a compound with the general formula AlX. Element X is a diatomic gas at
room temperature. Element X must be ______.
A) sulfur B) chlorine C) fluorine D) nitrogen E) oxygen
16. There are _______ atoms of oxygen in 300 molecules of CH3CO2H.
A) 1.80x1026 B) 300 C) 3.01x1024 D) 600 E) 6.02x1023
17. A compound that is composed of only carbon and hydrogen contains 85.7% C and 14.3% H by mass. What is the empirical formula of the
compound?
A) CH2 B) C2H4 C) C4H8 D) CH4
18. A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular
formula of this compound is________.
A) CH2O B) C2H4O2 C) C2H2O4 D) CHO2 E) C2H3O4
19. Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide: 4Al (s) + 3O2 (g)  2Al2O3 (s)
In a particular experiment, the reaction of 2.5 g of Al with 2.5 g of O2 produced 3.5 g of Al2O3. The % yield of the reaction is ____.
A) 74
B) 37
C) 26
D) 47
E) 66
20. Lead carbonate decomposes to give lead oxide and carbon dioxide:
PbCO3 (s)  PbO (s) + CO2 (g)
How many grams of lead oxide will be produced by the decomposition of 2.50 g of lead carbonate?
A) 0.00936 B) 2.50 C) 2.61 D) 0.41 E) 2.09
21. When the following equation is balanced, the coefficient of H2O is_____.
PCl3 + H2O  H3PO3 +HCl
A) 1 B) 4 C) 3 D) 2 E) 5
22. How many moles of carbon dioxide are there in 92.06 g of carbon dioxide?
A) 2.092 B) 1.183 C) 2.092x1023 D) 6.02x1023 E) 3.01x1023
23. There are _____ mols of carbon atoms in 4 mol of dimethylsulfoxide (C2H6SO).
A) 2 B) 6 C) 8 D) 3 E) 4
24. How many moles of sodium carbonate (Na2CO3) contain 3.01x1017 carbon atoms?
A) 8.84x10-7 B) 5.00x107 C) 8.84x107 D) 5.00x10-7 E) 2.0
25. What volume (mL) of a concentrated solution of sodium hydroxide (6.00 M) must be diluted to 200 mL to make a 0.88 M solution of
sodium hydroxide?
A) 2.64 B) 29.3 C) 26.4 D) 176 E) 50.0
26. One method for removal of metal ions from a solution is to convert the metal to its elemental form so it can be filtered out as a solid. Which
metal can be used to remove aluminum ions from solution?
A) cobalt B) copper C) lead D) zinc E) none of these
27. What is the concentration of chloride ions in a 0.193 M solution of potassium chloride?
A) 0.579 M B) 0.193 M C) 0.386 M D) 0.0965 M E) 0.0643 M
28. A 25.5 mL aliquot of HCl solution of unknown concentration was titrated with 0.113 M NaOH solution. It took 51.2 mL of the base to
reach the endpoint of the titration. What was the concentration (M) of the acid?
A) 1.02 B) 0.113 C) 0.227 D) 0.120 E) 0.454
29. The balanced reaction between aqueous nitric acid and aqueous strontium hydroxide is:
A) HNO3 (aq) + Sr(OH)2 (aq)  Sr(NO3)2 (aq) + H2 (g)
B) HNO3 (aq) + SrOH (aq)  H2O (l) + SrNO3 (aq)
C) 2HNO3 (aq) + Sr(OH)2 (aq)  2H2O (l) + Sr(NO3)2 (aq) D) HNO3 (aq) + Sr(OH)2 (aq)  H2O (l) + Sr(NO3)2 (aq)
E) 2HNO3 (aq) + Sr(OH)2 (aq)  Sr(NO3)2 (aq) + 2H2 (g)
30. How many grams of sodium chloride are there in 55.0 mL of a 1.90 M aqueous solution of sodium chloride?
A) 6.11 B) 12.2 C) 3.21 D) 6.11x10 3 E) 0.105
31. Which compound has the atom with the highest oxidation number?
A) CaS B) MgSO3 C) NH4Cl D) KNO2 E) Na3N
32. What is the concentration (M) of a NaCl solution prepared by dissolving 9.3 g of NaCl in sufficient water to give 350 mL of solution?
A) 2.7x10-2 B) 18 C) 0.16 D) 27
E) 0.45
33. When aqueous solutions of _______ are mixed, a precipitate forms.
A) KOH and Ba(NO3)2 B) NiBr2 and AgNO3 C) Li2CO3 and CsI
D) NaI and KBr
E) K2SO4 and CrCl3
34. What are the spectator ions in the reaction between KOH (aq) and HNO3 (aq)?
A) H+ and OH- B) K+ and NO3- C) K+ and H+ D) OH- only E) H+ and NO335. A strong electrolyte is one that ________ completely in solution.
A) disappears B) ionizes C) dissolves D) decomposes E) reacts
36. What is the molarity (M) of an aqueous solution containing 52.5 g of sucrose (C 12H22O11) in 35.5 mL of solution?
A) 1.48 B) 5.46 C) 0.104 D) 1.85 E) 4.32
GOOD LUCK!