CHEMISTRY 110 EXAM 2 Feb 25, 2013

FORM A --------------------------------------------------------------------------------- 1. How many valence electrons and lone pairs are in the structure

of the ammonium ion?   #  valence  

electrons  #  lone  pairs  

A.     8   0  B.     10   1  C.     8   1  D.     10   2  E.     12   3  

--------------------------------------------------------------------------------- 2. Which of the following best represents the molecular structure

of COS?

A. I B. II C. III D. II and III are equally good representations. E. I and II are equally good representations.

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--------------------------------------------------------------------------------- 3. What is the arrangement of electron domains about the

central atom in formaldehyde, H2CO? A. Tetrahedral B. Trigonal planar C. Square planar D. Trigonal bipyramidal E. Linear

--------------------------------------------------------------------------------- 4. Which of these molecules is/are non-polar?

A. I only B. II only C. IV only D. I and IV E. II and III

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Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

I II III IV

--------------------------------------------------------------------------------- 5. What functional groups are present in the molecule below:

A. alcohol, amine, aldehyde B. amine, aldehyde, ketone C. amine, ketone, carboxylic acid D. alcohol, ketone, carboxylic acid E. ketone, carboxylic acid, ester

--------------------------------------------------------------------------------- 6. What is the correct molecular formula for the following molecule:

A. C4H8O2 B. C4H10O2 C. C5H8O2 D. C5H10O2 E. None of the answers listed here are correct

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--------------------------------------------------------------------------------- 7. Which one of the following organic molecules would not have

dipole-dipole interactions as one of its intermolecular forces?

--------------------------------------------------------------------------------- 8. Which one of the following molecules is nonpolar?

A. NH3 B. OF2 C. CH3Cl D. H2O E. BeCl2

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OH

OH

O O

O

NH2

A. B. C.

D. E.

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--------------------------------------------------------------------------------- 9. What is the hybridization of As in the AsF4

– ion?

A. sp B. sp2 C. sp3 D. sp3d E. sp3d2

--------------------------------------------------------------------------------- 10. The structure of citric acid is given below. What is the

hybridization of the two labeled carbons? ?

  1   2  A.     sp   sp2  B.     sp2   sp3  C.     sp3   sp2  D.     sp3   sp  E.     sp2   sp2  

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--------------------------------------------------------------------------------- 11. Arrange the following substances in order of increasing

boiling point.

A. i < ii < iii B. i < iii < ii C. ii < iii < i D. iii < i < ii E. iii < ii < i

--------------------------------------------------------------------------------- 12. What is the percent carbon by mass in the compound below?

A. 39.4% B. 42.2% C. 51.7% D. 56.3% E. 62.3 %

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i. ii. iii.

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--------------------------------------------------------------------------------- 13. Select the electron-domain geometry and molecular geometry

of chlorine in the perchlorate ion, ClO4−.

  Electron  domain  

geometry  molecular  geometry  

A.     trigonal  planar   tetrahedral  B.     trigonal  planar   trigonal  planar  C.     tetrahedral   tetrahedral  D.     trigonal  pyramidal   trigonal  pyramidal  E.     trigonal  pyramidal   trigonal  planar  

--------------------------------------------------------------------------------- 14. Which of the following molecules are isomers?

A. I and II only B. II and III only C. I and IV only D. I, II, and III E. All of them

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--------------------------------------------------------------------------------- 15. As bond order increases, the strength of a covalent bond

_________ and bond length ______________.

As bond order increases  strength   length  

A.     increases   increases  B.     decreases   decreases  C.     increases   decreases  D.     decreases   increases  E.     increases   remains  constant  

--------------------------------------------------------------------------------- 16. Which of the following have one or more atoms in the

structure that have exceptions to the octet rule? BF3 NF3 SiF4 XeF4

A. BF3 and NF3 B. NF3 and SiF4 C. SiF4 and XeF4 D. BF3 and XeF4 E. NF3 and XeF4

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--------------------------------------------------------------------------------- 17. Which of the following contains the largest Y-X-Y bond

angle where X is the central atom of the molecule?

A. BF3 B. SiCl4 C. NH3 D. H2O E. They all have the same bond angle.

--------------------------------------------------------------------------------- 18. Which of the following molecules has a trigonal planar

structure?

1. CO32− 2. SOCl2 3. H3O+ 4. SO3

A. 1 only B. 1 and 4 C. 1, 2 and 3 D. 1, 3 and 4 E. all 4

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--------------------------------------------------------------------------------- 19. Rank the indicated bond angles in the molecule shown below

in order of increasing bond angle. (Lone pairs are NOT explicitly shown.)

A. 1 < 4 < 3 < 2 B. 3 < 1 < 2 ≈ 4 C. 4 = 1 < 2 < 3 D. 4 = 1 < 2 = 3 E. 3 < 4 < 1 < 2

--------------------------------------------------------------------------------- 20. What is the total number of σ and π-bonds in the following

molecule?

H C C C C C N− ≡ − ≡ − ≡

  σ   π  A.     6   3  B.     3   3  C.     6   6  D.     3   6  E.     3   9  

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C

H

H

H C

O

O O N

H

H

1

2

3 4

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--------------------------------------------------------------------------------- 21. Which of the following molecules will exhibit delocalized π-

bonding? I. SO II. SO2 III. SO3

A. I only B. II only C. III only D. I and II E. II and III

--------------------------------------------------------------------------------- 22. Which one of these molecule has the smallest % oxygen by mass?

A. I B. II C. III D. IV E. I and IV have the same and the smallest % oxygen

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--------------------------------------------------------------------------------- 23. Draw Lewis structures for NO2

+, NO2− and NO3

−. Based on the interpretation of the Lewis structures, put these in order of increasing bond order?

A. NO2

+ < NO2− = NO3

− B. NO2

+ < NO3− < NO2

− C. NO2

− = NO3− < NO2

+ D. NO3

− < NO2− < NO2

+ E. NO2

− < NO2+ < NO3

− --------------------------------------------------------------------------------- 24. How are the molecules below related to the molecule shown above? Are they a geometric isomer, a structural isomer or neither?

  I   II   III  A.     neither   structural   geometric  B.     neither   geometric   structural  C.     geometric   geometric   structural  D.     structural   structural   geometric  E.     geometric   structural   geometric  

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C C

CH OH

H

CH3

H

H

C C

C CH3

O

H3C

H

H

C C

CH OH

H

H

H

CH3

C C

CH OH

H

H

H3C

H

I II III

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--------------------------------------------------------------------------------- 25. Which of the following are pairs of resonance structures?

A. I only B. II only C. III only D. I and II E. II and III

--------------------------------------------------------------------------------- 26. What is the electron domain geometry of a molecule that only

contains S and F and is 29.67% S by weight?

A. Octahedral B. Trigonal planar C. Linear D. Tetrahedral E. Trigonal bipyramidal

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--------------------------------------------------------------------------------- 27. Which one of these correctly depicts hydrogen bonding in

acetic acid (CH3COOH)? The dashed line ( ) represent the hydrogen bond.

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Boiling point

i 174 °C

ii. 219 °C

iii. 285 °C

28. The boiling points of the three molecules shown are given

below their structures. Which of these statements are true?

I. The first molecule (i) has the greatest dipole moment of the three.

II. As the polarity increases the boiling point increases. III. As the London dispersion forces increase, the

boiling point increases.

A. I only B. II only C. III only D. I and II E. I and III

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Cl

Cl

Br

Br

I

I

CHEMISTRY 110 EXAM 2 February 25, 2013

Answer Key FORM A 1. A 2. B 3. B 4. D 5. D 6. D 7. B 8. E 9. D 10. C 11. A 12. D 13. C 14. E 15. C 16. D 17. A 18. B 19. E 20. C 21. E 22. B 23. D 24. A 25. C 26. E 27. B, D and E = full credit 28. E