Exam Problem Set 1

Select an answer for each of the 48 multiple-choice questions below, then press Check Answers. The answer key unlocks after a genuine attempt.

General and Miscellaneous

1. How many electrons occupy the bonding molecular orbitals of a CN triple bond?
A) 2 B) 4 C) 6 D) 8

2. Which of the following species is not amphoteric ?
A) NH₃ B) HF C) NH₄⁽⁺⁾ D) HCO₃^(-)

3 What is the relationship of the two structures shown below?
Two condensed structural formulas of branched C10 alkane isomers shown side by side for comparison
A) they are identical.
B) they are conformations of the same structure
C) they are constitutional isomers.
D) they are different compounds with different compositions

4 Which of the following molecules will not have a dipole moment?
A) CH₃Cl
B) CH₃OCH₃
C) CH₂Cl₂
D) CCl₄

5 Which of the following molecules has a dipole moment?
A) CBr₄
B) CH₂=CH₂
C) BF₃
D) SO₂

6 Which of the following molecules has a linear shape?
A) NH₃
B) H₂S
C) CO₂
D) H₂CO

7 Which of the following intermediates is pyramidal in shape?
A) H₃C(+)
B) H₂C:
C) H₃C:(-)
D) HC≡C:(-)

8 In which compound does carbon have the highest oxidation state?
A) CH₄
B) HCN
C) H₂CO
D) CH₂Cl₂

9 Which of the following statements applies to a C₁₀H₁₄O₂ compound?
A) it may have 2 double bonds and 2 rings
B) it may have 3 double bonds and 0 rings
C) it may have 1 triple bond and 3 rings
D) it may have 0 double bonds and 3 rings

10 What functional group is present in the terpene camphor?
Bicyclic skeletal structure of camphor showing a ketone carbonyl group
A) hydroxy
B) carboxy
C) carbonyl
D) oxy

11 What functional class is represented by the alkaloid coniine?
Skeletal structure of coniine, a 2-propylpiperidine with a ring NH amine group
A) amine
B) imine
C) amide
D) nitrile

12 Which of the following compounds would be considered an electrophilic reagent?
A) NH₃
B) Br₂
C) CH₃OH
D) NH₂OH

13 Which of the following compounds would you expect to be most soluble in water?
A) CH₂Cl₂
B) C₆H₁₂ (cyclohexane)
C) CH₃CH₂OH
D) C₂H₅OC₂H₅

14 The following compounds have similar molecular weights. Which has the highest boiling point?
A) CH₃CH=O
B) C₂H₅OH
C) CH₃OCH₃
D) CH₃CH₂CH₃

15 Which of the following compound pairs are constitutional isomers?
A) CH₃CH₂OCH₃ and CH₃CH₂CHO
B) CH₃CH₂CHO and CH₃CH₂CH₂OH
C) CH₃COCH₂CH₃ and CH₃CH₂COCH₃
D) CH₃CH₂CH₂CHO and CH₃COCH₂CH₃

16 Which of the following compounds may be classed as a protic solvent?
A) tert-butanol
B) diethyl ether
C) n-hexane
D) acetone

17 Classify the following reaction.
Cyclohexanone plus HCN reacting to form 1-hydroxycyclohexanecarbonitrile (cyanohydrin)
A) substitution
B) addition
C) elimination
D) rearrangement

18 Which of the following is not a nucleophile?
A) H₂O
B) CH₃NH₂
C) C₂H₅SH
D) C₆H₁₂ (cyclohexane)

19 Which of the following is not an electrophile?
A) C₂H₅OC₂H₅
B) BF₃
C) [CH₃]₃C⁽⁺⁾
D) HOCl

20 Which Lewis formula is the best representation of N₂O?


(A)	(B)	(C)	(D)

21 Which of the following compounds has a C-H bond with the lowest bond dissociation energy?
A) C₂H₆
B) C₆H₆
C) C₂H₂
D) CH₃CH=CH₂

22 In order for a reagent to behave as a nucleophile it must have ...
A) an overall positive charge.
B) an overall negative charge.
C) a non-bonding electron pair.
D) a nitrogen or sulfur atom.

23 The H–C–O bond angle in H₂C=O (formaldehyde) is approximately .....
A) 90º
B) 109º.
C) 120º.
D) 180º.

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

25 Which of the following molecular formulas is reasonable for a stable compound?
A) C₈H₁₄O₂Cl
B) C₆H₁₄Br₂
C) C₇H₁₀NF
D) C₃₀H₅₄N₂Cl

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)
A) N is -1 and C is +1
B) N is +1 and C is -1
C) O is -1 and C is +1
D) O is -1 and N is +1

27 Which statement about members of a homologous series is true ?
A) they are all constitutional isomers.
B) they are always hydrocarbons.
C) each differs from its nearest neighbors by 14 amu.
D) they may also be classified as tautomers.

28 How many structurally distinct (different) sets of hydrogens are present in (CH₃)₃CCH₂OCH₃?
A) 2
B) 3
C) 4
D) 8

29 The pK_as of H₂CO₃ are 6.4 & 10.3. The pK_a 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?
A) HCO₃^-1 and BrO^-1
B) CO₃^-2, Br^-1 and OH^-1
C) HCO₃^-1 and Br^-1
D) CO₃^-2 and 2 BrO^-1

30 Which of the following is a conjugate base of CH₃NHOH?
A) CH₃NH^-1
B) CH₃NHO^-1
C) CH₃NH₃⁺¹
D) CH₂=NOH^-1

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 ?

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 ?

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

Energy vs reaction diagram of a two-step reaction with two peaks; activation energies X and Y marked

A) A two-step exothermic reaction having an activation energy = X
B) A two-step endothermic reaction having an activation energy = Y
C) A two-step exothermic reaction having an activation energy = Y
D) A two-step endothermic reaction having an activation energy = X

34 Which of the following series contain a free radical, a nucleophile and an electrophile?
A) Br· BF₃ NH₃
B) NH₃ NO₂⁺ Br₂
C) H₂O Cl· NH₃
D) Cl₂ CH₄ NH₃

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 ?

36 Which of the following species has a planar molecular configuration?
A) SO₃^-2
B) SO₃
C) SOCl₂
D) SO₂Cl₂

37 Which of the following compounds does not have a planar molecular configuration?
A) H₂C=CH₂
B) H₂C=CH–C≡CH
C) H₂C=C=CH₂
D) H₂C=C=C=CH₂

38 How many degrees of unsaturation does the following structure have?
Skeletal structure of a tetrahydroquinoline with a hydroxyl and ethynyl group, for counting degrees of unsaturation
A) 4
B) 5
C) 6
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?
Structure of vitamin C (ascorbic acid) with four hydroxyl groups numbered 1-4 by shaded circles
A) 1
B) 2
C) 3
D) 4

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

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?
Four resonance contributors I-IV of a carbonyl oxide ozonolysis intermediate with formal charges
A) III is most favorable & II is least favorable
B) I is most favorable & IV is least favorable
C) II is most favorable & IV is least favorable
D) I is most favorable & II is least favorable

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?
A) The double bond would have the same strength as the single bond.
B) The double bond would be stronger than, but less than twice as strong as the single bond.
C) The double bond would have exactly twice the strength of the single bond.
D) The double bond would have more than twice the strength of the single bond.

43 Which of the following cations is most stable?
A) FH₂⁺
B) OH₃⁺
C) NH₄⁺
D) CH₅⁺

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?
A) C₁₀H₈O₄Cl₄
B) C₁₂H₆O₂Cl₄
C) C₆H₂OCl₂
D) C₁₂H₄O₂Cl₄

45 Which of the following covalent compounds does not have any formally charged atoms?
A) (CH₃)₃NO
B) CH₂=N=N
C) CH₃-O-N=O
D) CH₃C≡NO

46 Which of the following statements is not generally correct?
A) endothermic reactions have larger energies of activation than exothermic reactions
B) the rate of a reaction is proportional to its activation energy
C) the rate of a reaction generally increases as the temperature is raised
D) all reactions in which bonds are broken and formed have a significant activation energy

47 Which of the following compounds has no isomer?
A) CH₃CH₂CH₂Cl
B) CH₃CHO
C) CH₂=CHCl
D) ClCH₂CH₂Cl

48 Which of the following statements about carbon is not correct?
A) carbon forms strong covalent bonds to itself, allowing chains and rings to be made.
B) carbon expands its valence shell to accomodate more than eight electrons and thus forms double and triple bonds.
C) carbon forms strong covalent bonds to elements like nitrogen and oxygen because it does not have lone pairs of valence electrons to destabilize the bonds.
D) carbon and hydrogen have similar electronegativity and form strong bonds to each other, thus avoiding the high reactivity shown by metal hydrides.

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