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1. An atom with an electron configuration of 1s² Ìý2s² Ìý2p³ Ìýhas how many valence electrons?
   Khan Academy:Ìý ; Wyzant:Ìý Ìý
   1. 2
   2. 3
   3. 4
   4. 5Ìý (must use highest shell electrons only—2+3)
   5. 7
2. TheÌý ___ sublevel of an atom has a total of five orbitals.
   Khan Academy:Ìý ; Wyzant:Ìý
   
   1. sÌý (all s-sublevels have just one orbital)
   2. pÌý (all p-sublevels have three orbitals)
   3. d
   4. fÌý (all f-sublevels have seven orbitals)
   5. gÌý (all g-sublevels have nine orbitals)
3. You give a child a balloon, and he goes outside with it to play in the snow. Soon, he returns crying. What happened?
   Khan Academy:Ìý ; Wyzant:Ìý
   1. The balloon expanded and burst.
   2. The balloon froze solid.
   3. The balloon shrank.Ìý (pressure and temperature directly proportional)
   4. The balloon dissolved.
   5. The child forgot Charles’ Law.
4. What kind of bonding occurs in the compound potassium oxide?
   Khan Academy:Ìý
   
   1. ionicÌý (strongly metallic elements, K, and electronegative nonmetals, O, form ionic bonds)
   2. nonpolar covalent
   3. polar covalent Ìý(double bond)
   4. polar covalentÌý (single bond)
   5. None of the above
5. A gas with a temperature of 21.0^oC and a volume of 10.0 L is compressed to 5.00 L. What will be the new temperature?
   Khan Academy:Ìý ; Wyzant:Ìý
   
   1. 10.5Ìý ^oCÌý (don’t forget to change temperatures to Kelvin)
   2. 420.Ìý ^oCÌý (don’t forget how to change to Kelvin back to Celsius)
   3. 42.0Ìý ^oCÌý (several of the above went wrong!)
   4. –126Ìý ^oC
   5. 315Ìý ^oCÌý (mixed up initial and final conditions)
6. Which of the following sublevels does not exist as written?
   Khan Academy:Ìý
   
   1. 3fÌý (the fourth f-sublevel appears for the first time in the fourth shell)
   2. 6f
   3. 2s
   4. 5d
   5. 8sÌý (the number of sublevels—s, p, d, f, etc.—increase by one as the main energy level increases by one)
7. What is the molecular shape of PH₃?Ìý
   Khan Academy:Ìý
   
   1. tetrahedralÌý (the lone electron pair isn’t counted in the shape)
   2. trigonal planarÌý (don’t forget to include the lone electron pair)
   3. bent
   4. linear
   5. trigonal pyramidal
8. What is the percent by mass concentration of sodium bromide in a solution which contains 50.0 g of sodium bromide in 200.0 g of water?
   Wyzant:Ìý
   
   1. 40.0 %
   2. 20.0 %
   3. 25.0 % Ìý(forgot to add 50+250 for the total solution mass)
   4. 33.3 %
   5. 50.0 %
9. How many milliliters of 6.00Ìý MÌý HCl solution would be required to prepare 2.00 L of 0.140 M HCl by dilution?
   Wyzant:Ìý
   
   1. 420 mLÌý (mixed up which volume needed to calculate total moles HCl)
   2. 168 mL
   3. 85.6 mLÌý (moles x volume gives moles)
   4. 46.7 mLÌý (2.00 x 0.140 gives total moles HCl; dividing that by 6.00 gives volume needed)
   5. 30.0 mL
10. What is the molar concentration of 2000. mL of aqueous solution containing 135 g of glucose, C6H12O6?
    Wyzant:Ìý ; Khan Academy:Ìý
    1. 12.15 M Ìý(don’t forget how to correctly convert grams to moles)
    2. 0.750 M
    3. 67.5 M Ìý(don’t forget to change grams to moles)
    4. 0.667 M
    5. 0.375 MÌý
11. What is the formula of copper (II) sulfate pentahydrate?
    Wyzant:Ìý
    1. Cu₂(SO₄)₂ Ìý. 5 H₂OÌý (ionic compounds written with simplest subscripts)
    2. Cu₂(SO₄) . 5 H₂OÌý(wrong charges on your ions)
    3. CuSO₄Ìý. 6 H₂OÌý(hexahydrate would be the correct name here)
    4. CuSO₄Ìý. 5 H₂O
    5. None of the above
12. What is the electron configuration for the nitride ion?
    Khan Academy:Ìý ; Wyzant:Ìý
    1. 1s² Ìý2s² Ìý2p¹
    2. 1s² Ìý2s² Ìý2p³ Ìý(this is just a nitrogen atom by itself)
    3. 1s² Ìý2s² Ìý2p⁵ Ìý(nitrogen needs to add three electrons to achieve the noble gas configuration)
    4. 1s² Ìý2s² Ìý2p⁶ Ìý(nitride has a negative three charge—adding three electrons to the N-atom)
    5. None of the above
13. A tank has a pressure of 30.0 atm at a temperature of 22.0oC. After heating, the temperature rises to
    35.0^oC. What is the new pressure?
    Khan Academy:Ìý ; Wyzant:Ìý
    1. 54.3 atm
    2. 31.3 atm
    3. 28.7 atmÌý (mixed up initial and final conditions—pressure should go up!)
    4. 47.7 atmÌý (don’t forget to change temperature to Kelvin)
    5. 30.6 atm
14. Which pair is immiscible?
    Wyzant:Ìý ; Khan Academy:Ìý
    1. ethanol and waterÌý (both are polar)
    2. water and octane, C₈H₁₈Ìý(like dissolves like—water is polar, while octane is nonpolar)
    3. isopropyl alcohol and water
    4. acetic acid and waterÌý (both are polar)
    5. octane and oilÌý (both are nonpolar)
15. How many grams of sodium hydroxide are required to prepare 250.0 mL of a 6.00 M solution?
    Wyzant:Ìý ; Khan Academy:Ìý
    1. 1.50 g Ìý(these are the moles of sodium hydroxide needed—be sure to convert to grams)
    2. 0.0375 gÌý (don’t forget how to convert moles to grams)
    3. 0.600 g Ìý(incorrect conversion of mL to L)
    4. 3.75 gÌý (combined errors from b and c)
    5. 60.0 gÌý
16. 5.60 L of a gas at STP has a mass of 13.0 g. What is the molar mass of the gas?
    Khan Academy:Ìý ; Wyzant:Ìý
    
    1. 33.2 g/mol Ìý(keep in mind that STP = 273 K, 1 atm)
    2. 66.4 g/molÌý (1 mol of gas at STP = 22.4 L)
    3. 26.0 g/mol
    4. 52.0 g/mol
    5. none of the above
17. What volume of 0.62Ìý MÌý sodium hydroxide is required to neutralize 20.00 mL of 0.391Ìý MÌý nitric acid? Word reaction with reactantsÌý only. (Students should predict products): Sodium hydroxide + nitric acidÌý
    Khan Academy:Ìý ; Wyzant:Ìý ; Wyzant:
    
    1. 23.6 mL
    2. 16.9 mL
    3. 9.03 mL
    4. 11.8 mL
    5. none of the aboveÌý (correct amount is 12.6 mL; the two reactants are in a 1:1 mol ratio)
18. How many moles are in 20.0 g of sodium carbonate?
    Khan Academy:Ìý ; Wyzant:Ìý
    1. 1.89 molÌý (no unit conversions of grams are required)
    2. 212 mol
    3. 2.12 x 10³ÌýmolÌý (remember how to correctly convert grams to moles)
    4. 0.189 mol
    5. 18.9 mol Ìý(no unit conversions of grams are required)
19. The percent of nitrogen in magnesium nitride is
    Khan Academy:Ìý ; Wyzant:Ìý ; ÌýWyzant:
    1. 27.8%
    2. 36.6%Ìý (write correct formula for compound, remembering monatomic charges)
    3. 16.1%
    4. 72.2%Ìý (this is the mass percent of magnesium)
    5. 63.4%Ìý (write correct formula for compound, remembering monatomic charges)
20. What is the molar concentration of 250. mL of aqueous solution containing 48.8 g of glucose, C6H12O6?
    Wyzant:Ìý ; Khan Academy:Ìý
    1. 5.12 M Ìý(combination of errors from b and e)
    2. 0.923 MÌý (inverted the definition of molarity = moles ÷ volume in liters)
    3. 0.271 M
    4. 1.08 M
    5. 0.195 M Ìý(must convert grams to moles first)Ìý
21. How many grams of aluminum metal will react with 0.0500 mole of oxygen gas according to the unbalanced equation given? Aluminum + Oxygen -> Aluminum Oxide
    Khan Academy:Ìý ; Wyzant:Ìý
    1. 1.35 gÌý (first balance equation to convert moles diatomic oxygen to moles aluminum)
    2. 1.01 g
    3. 4.32 g
    4. 2.06 g
    5. 1.80 g
22. For the equation given, how many grams of methane will react with 125 g of oxygen? Word reaction with reactantsÌý only. (Students should predict products):
    Methane (CH₄) burns in oxygen
    Khan Academy:Ìý ; Wyzant:Ìý
    1. 39.1 g
    2. 19.5 g
    3. 15.6 g
    4. 31.3 g
    5. 62.5 gÌý (must use diatomic oxygen and its molar mass in this calculation)
23. For problems 24 - 25, Given the word reaction with reactants only (students should predict products): phosphoric acid reacts with magnesium carbonate
24. From the balanced chemical equation the simplest whole number coefficient for the product magnesium phosphate is:
    Khan Academy:Ìý ; Wyzant:Ìý
    1. 1
    2. 2Ìý (be sure to use correct charges on ions when balancing)
    3. 3
    4. 4
    5. none of the above
25. If 50.0 g of magnesium carbonate reacts completely with phosphoric acid, the grams of gas produced is:
    Khan Academy:Ìý ; Wyzant:Ìý ; ÌýWyzant:
    
    1. 52.2 g
    2. 26.1 g
    3. 13.1 g
    4. 50.0 gÌý (balance the equation to start, then convert reactant grams to moles)
    5. 55.0 gÌý (the gas produced is carbon dioxide, molar mass = 44.01 g/mol)
26. How many molecules are in 5.8 g of acetone, C₃H₆O?
    Khan Academy:Ìý ; ChemTutor:Ìý
    1. 0.10 moleculesÌý (this is the number of moles, not molecules)
    2. 6.0 x 1022 molecules
    3. 3.5 x 1024 molecules
    4. 6.0 x 1023 moleculesÌý (this is roughly Avogadro’s number, the number molecules in a mol)
    5. none of the above
27. This reaction is an example of which of the following types? Aluminum reacts with bromine to produce aluminum bromide
    Wyzant:Ìý
    1. combinationÌý (two or more reactants produce a single product)
    2. single displacement
    3. decomposition
    4. gas formation
    5. precipitation
28. What is the simplest whole number coefficient for aluminum bromide in the above reaction (#27)?
    Khan Academy:Ìý ; Wyzant:Ìý
    
    1. 1Ìý (recall that bromine is diatomic, as well as the correct charges on the monatomic ions)
    2. 2
    3. 3
    4. 4
    5. none of the above
29. How many moles of oxygen are required for the complete reaction of 45 g of C₂H₄ Ìýwhen it is burned?
    Khan Academy:Ìý , Khan Academy: ; Wyzant:Ìý ; ÌýWyzant:
    1. 1.3 x 102 molÌý (balance the equation to start, then convert reactant grams to moles)
    2. 0.64 mol
    3. 112.4 mol
    4. 4.8 mol
    5. none of the above
30. If 14.0 g of C₂H₄ Ìýis burned and the actual yield of water is 7.84 g, the percent yield in the reaction is:Ìý
    Khan Academy:Ìý; Khan Academy: ;ÌýWyzant:Ìý ; ÌýWyzant:
    1. 0.56%
    2. 43.6%
    3. 87.1% (be sure to balance the equation and convert moles reactant to moles product)
    4. 56.0%
    5. 82.0%