ACS ochem 2

20 Which Lewis formula is the best representation of N2O?

20A

24 Which of the following structural pairs represents contributors to a resonance hybrid?

24A

28 How many structurally distinct (different) sets of hydrogens are present in (CH3)3CCH2OCH3?

3

31 A Lewis formula for diazomethane, CH2N2, is shown on the left below.Which of the formulas within the brackets would be considered a proper resonance contributor to this structure ?

31B

32 The curved arrows in the formula on the left represent a chemical reaction.Which of the formulas within the brackets would constitute the product(s) from this reaction ?

32D

35 The curved arrows in the formula on the left represent a chemical reaction.Which of the formulas within the brackets would constitute the product(s) from this reaction ?

35C

1. How many electrons occupy the bonding molecular orbitals of a CN triple bond?

6

13 The most typical reaction of simple alkenes is ...

A) electrophilic substitution

37 Which of the following compounds does not have a planar molecular configuration?

H2C=C=CH2

7 Which of the following intermediates is pyramidal in shape?

H3C:(-)

8 In which compound does carbon have the highest oxidation state?

HCN

29 The pKas of H2CO3 are 6.4 & 10.3. The pKa of HOBr is 8.7. If equimolar amounts of Na2CO3 and HOBr are dissolved in water what will be the predominant anionic species in the resulting solution?

HCO3-1 and BrO-1

41 The following structures are resonance contributors for a reactive intermediate formed during ozonolysis of alkenes. Identify the most energetically favorable and the least favorable contributors?

I is most favorable & IV is least favorable

40 Which of the following structures is not a resonance contributor to the hybrid defined by the other three?

40A

48 Which of the following statements about carbon is not correct?

carbon expands its valence shell to accomodate more than eight electrons and thus forms double and triple bonds.

10 What functional group is present in the terpene camphor?

carbonyl

46 Which of the following statements is not generally correct?

endothermic reactions have larger energies of activation than exothermic reactions

23 The H-C-O bond angle in H2C=O (formaldehyde) is approximately .....

120º.

38 How many degrees of unsaturation does the following structure have?

38D D) 7

39 The structural formula for vitamin C is shown below Of the four hydroxyl groups, identified by shaded circles, which is most acidic?

39C C) 3

2. Which of the following species is not amphoteric ? (of a compound, especially a metal oxide or hydroxide) able to react both as a base and as an acid.

NH4(+)

43 Which of the following cations is most stable?

NH4+

27 Which statement about members of a homologous series is true ?

each differs from its nearest neighbors by 14 amu.

3 What is the relationship of the two structures shown below?

they are identical.

4 Which of the following molecules will not have a dipole moment?

CCl4

47 Which of the following compounds has no isomer?

CH2=CHCl

45 Which of the following covalent compounds does not have any formally charged atoms?

CH3-O-N=O

15 Which of the following compound pairs are constitutional isomers?

CH3CH2CH2CHO and CH3COCH2CH3

13 Which of the following compounds would you expect to be most soluble in water?

CH3CH2OH

21 Which of the following compounds has a C-H bond with the lowest bond dissociation energy?

CH3CH=CH2

30 Which of the following is a conjugate base of CH3NHOH?

CH3NHO-1

6 Which of the following molecules has a linear shape?

CO2

44 The toxic environmental pollutant dioxin is 44.8% carbon, 1.25% hydrogen and 44.0% chlorine. Its molecular weight is 320±10 What is the molecular formula of dioxin?

C12H4O2Cl4

16 Which of the following compounds may be classed as a protic solvent?

tert-butanol

18 Which of the following is not a nucleophile?

C6H12 (cyclohexane)

12 Which of the following compounds would be considered an electrophilic reagent?

Br2

34 Which of the following series contain a free radical, a nucleophile and an electrophile?

Br· BF3 NH3

33 Which of the descriptions (A to D) correctly describe the following energy diagram?

A two-step endothermic reaction having an activation energy = X

19 Which of the following is not an electrophile?

C2H5OC2H5

14 The following compounds have similar molecular weights. Which has the highest boiling point?

C2H5OH

25 Which of the following molecular formulas is reasonable for a stable compound?

C7H10NF

26 What formal charges are present in the molecule C6H5C≡N-O? ( all heavy atoms have a valence shell octet, and C6H5- is a phenyl group)

O is -1 and N is +1

5 Which of the following molecules has a dipole moment?

SO2

36 Which of the following species has a planar molecular configuration?

SO3

42 How would the bond strength of the C:C double bond in an alkene compare to that of a C:C single bond in the corresponding alkane?

The double bond would be stronger than, but less than twice as strong as the single bond.

22 In order for a reagent to behave as a nucleophile it must have ...

a non-bonding electron pair.

17 Classify the following reaction.

addition

11 What functional class is represented by the alkaloid coniine?

amine

9 Which of the following statements applies to a C10H14O2 compound?

it may have 2 double bonds and 2 rings