Directions: Please circle the best answer for each of the following questions




НазваDirections: Please circle the best answer for each of the following questions
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Grossmont College Name _____________________________

Chemistry 120

Spring 2011 Lab Day___________ Date ____________


Exam 2


Part I: Multiple Choice (2 points each)

Directions: Please circle the best answer for each of the following questions.



Question 1. An element that has four valence

electrons could form

  1. four single bonds.

  2. two double bonds.

  3. one single bond and one triple bond.

  4. more than one correct response

  5. no correct response


Question 2. Eighteen valence electrons are present in the Lewis structure of

  1. carbon dioxide

  2. dinitrogen monoxide

  3. sulfur dioxide

  4. lithium nitride

  5. barium phosphate


Question 3. Which ion pairing is the chemical formula given not consistent with the ionic charges?

  1. M2+ and X3-, M3X2

  2. M2+ and X-, MX2

  3. M+ and X3-, MX3

  4. all of the above

  5. none of the above


Question 4. Which of the following sets of information about a sample of a compound is sufficient to calculate the compound’s molar mass?

  1. contain nitrogen and oxygen; 1.23 moles are present

  2. 24.36 g and 0.300 moles is present;

  3. 5.6 x 1023atoms are present and 37.23 g are present

  4. all of the above

  5. none of the above


Question 5. What is the empirical formula for a compound whose molecular formula is C2H2O4?

  1. CHO

  2. C2H2O2

  3. C4H4O8

  4. C4H2O2

  5. none of the above


Question 6. Which of the following concept pairings relating to element classifications in incorrect?

  1. inner-transition element-distinguishing electron is found in a f subshell

  2. representative element-some are metals and some are nonmetals

  3. noble gas element-electron configurations ends in p5 or p6

  4. more than one correct response

  5. no correct response


Question 7. Which of the following is true about x?

  1. independent variable

  2. ordinate

  3. pressure

  4. Cartesian coordinate

  5. hyperbola


Question 8. One mole of dichlorine monoxide contains

  1. 16.00 g of O.

  2. 35.45 g of Cl.

  3. 70.90 g of Cl.

  4. a and c

  5. all of the above


Question 9. Which of the following are incorrectly written electron configurations?

  1. 1s2 2s2 2p2 3s2

  2. 1s2 2s2 2p6 3s2 3p2

  3. 1s2 2s2 2p6 3s2 3p6 4s2 3d5

  4. 1s1

  5. none of the above


Question 10. Which parts of the body are at-risk for exposure to chemicals?

  1. The face.

  2. Hands, arms, legs and feet.

  3. Midsection.

  4. Back.

  5. all of the above




Part II: Short Answer

Directions: Answer each of the following questions. Be sure to use complete sentences where appropriate. For full credit be sure to show all of your work.


Question 1. Technetium forms three monoatomic ions, Tc4+, Tc6+, Tc7+. From this sublevel do you expect electrons are lost in forming these ions? (Hint: It is possible for electrons other than those in the s and p sublevels to be involved in forming ions.) (7 points)

    1. In forming the Tc7+ ion are:

      1. electron(s) lost from the 4s orbital? _________




      1. electron(s) lost from the 5p orbital? __________




      1. electron(s) lost from the 4d orbital? __________




    1. To support your answer, complete the following. It is OK to use the noble gas core notation.

      1. Electron configuration of technetium: __________________




      1. Electron configuration of Tc4+ __________________


Question 2. If a 1.00 g sample of a carbon-containing compound is burned in air, 0.75 g of carbon dioxide (the only carbon-containing product) is produced. What is the mass percent carbon in the compound (6 points)?


Question 3. Draw electron orbital diagrams to show the distribution of electrons among orbitals in each of the following electron subshells (4 points):


          1. 3s subshell of Mg




          1. 3p subshell of Cl




          1. 4s subshell of K




          1. 3d subshell of Co


Question 4. Identify the bond of greatest polarity in each of the following set of bonds (4 points):



          1. H-Cl, H-O, H-Br




          1. O-F, O-P, O-Al




          1. H-Cl, Br-Br, B-N




          1. Al-Cl, C-N, Cl-F




Question 5. Based on periodic trends, indicate which member of each pair of elements is (5 points):


                1. more metallic Na or Rb




                1. has a larger atomic radius B or C




                1. more nonmetallic F or Br




                1. more electronegative Al or N




                1. lower first ionization energy Li or P


Question 6. Given the correct IUPAC name for the following compounds (10 points):


  1. PCl3 ____________________________________




  1. V2O5 ____________________________________




  1. RbClO4 ____________________________________




  1. H2CO3 (aq) ____________________________________




  1. MgSO4 • 6 H2O ____________________________________


Question 7. Write the correct formula for the following compounds (10 points):


  1. Stannous fluoride __________________




  1. Sodium phosphate __________________




  1. Cobalt(VI) nitrate __________________




  1. Hydrocyanic acid __________________




  1. Nickel(II) fluoride tetrahydrate __________________


Question 8. For each molecule: a) draw the Lewis structure; b) give the electron pair geometry; c) give the molecular shape; d) give the bond angle; e) identify the molecule as polar or nonpolar (14 points).

a. dichloromethane, CH2Cl2 b. carbon disulfide, CS2 c. nitryl chloride, ClNO2


Question 9. If 1.550 g of mercury oxide decomposes to give 1.435 g of liquid mercury and oxygen gas (12 points).

  1. What is the empirical formula of the mercury oxide?




  1. What is the empirical mass?




  1. What is the molecular formula if the molar mass of the compound is about 217 g/mol?




  1. What is the name of the compound? _________________________



Question 10. Specify the reason each of the following electron dot structures is incorrect. Draw correct structures (8 points).





















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