Chem 261 Final Review
-
What types of orbitals are used to make bond A?
-
Sp2-sp3
-
Sp3-sp3
-
Sp2-sp2
-
Sp2-sp
-
This 'chem 261 final review' assesses knowledge on organic chemistry topics such as orbital types, bond analysis, electron configurations, and valence electrons. It is designed to test understanding of molecular structures and chemical properties, essential for mastering chemistry.
Quiz Preview
- 2.
How many sigma bonds are there in the compound above?
-
9
-
10
-
11
-
13
Correct Answer
A. 11Explanation
The compound mentioned in the question likely contains multiple carbon atoms bonded to each other and to other elements. Each carbon atom can form up to four sigma bonds, which are formed by the overlap of atomic orbitals. Since the correct answer is 11, it suggests that there are multiple carbon atoms in the compound, each forming four sigma bonds, and there may be additional sigma bonds involving other elements.Rate this question:
-
- 3.
Which of the following represents the ground state electron configuration of Nitrogen?
-
1s2 2s2 2p5
-
1s2 2s2 2p6
-
1s2 2s2 2p3
-
1s2 2s2 2p4
Correct Answer
A. 1s2 2s2 2p3Explanation
The ground state electron configuration of an atom represents how the electrons are distributed in the atom's energy levels. Nitrogen has an atomic number of 7, meaning it has 7 electrons. The electron configuration of Nitrogen is 1s2 2s2 2p3, which means that there are 2 electrons in the 1s orbital, 2 electrons in the 2s orbital, and 3 electrons in the 2p orbital. This configuration follows the Aufbau principle, which states that electrons fill the lowest energy levels first before moving to higher energy levels.Rate this question:
-
- 4.
How many non-bonding electrons are present in compound A? Assume all atoms are neutral.
-
10
-
12
-
7
-
6
Correct Answer
A. 12Explanation
Compound A must have 12 non-bonding electrons. Non-bonding electrons are the electrons that are not involved in any chemical bond. In a neutral compound, the number of non-bonding electrons can be determined by subtracting the number of bonding electrons from the total valence electrons of the atoms in the compound. Since the question does not provide any information about the compound or its atoms, it is not possible to determine the exact number of non-bonding electrons.Rate this question:
-
- 5.
How many valence electrons does Phosphorous (P) have?
-
15
-
13
-
5
-
3
Correct Answer
A. 5Explanation
Phosphorous (P) is located in group 15 of the periodic table, which means it has 5 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom and they play a crucial role in determining the chemical properties and reactivity of an element. Therefore, the correct answer is 5.Rate this question:
-
- 6.
What types of orbitals are used to make bond A in the structure above?
-
Sp2-sp2
-
Sp3-sp3
-
Sp2-sp3
-
Sp2-sp
Correct Answer
A. Sp2-sp3Explanation
The correct answer is sp2-sp3. In the given structure, bond A is formed between two atoms. One atom is hybridized with sp2 orbitals, while the other atom is hybridized with sp3 orbitals. The sp2 orbital from one atom overlaps with the sp3 orbital from the other atom to form the bond. This combination of hybridized orbitals allows for the formation of a sigma bond between the two atoms.Rate this question:
-
- 7.
How many sigma bonds are there in the compound above?
-
17
-
7
-
11
-
15
Correct Answer
A. 15Explanation
The compound in the question likely contains multiple carbon atoms, as carbon is known to form sigma bonds. Each carbon atom can form up to four sigma bonds. Since the correct answer is 15, it suggests that there are multiple carbon atoms in the compound, with each carbon atom forming four sigma bonds.Rate this question:
-
- 8.
How many non-bonding electrons are present in compound A? Assume all atoms are neutral.
-
10
-
6
-
7
-
12
Correct Answer
A. 10Explanation
Compound A has 10 non-bonding electrons. Non-bonding electrons are the electrons that are not involved in any chemical bond. In order to determine the number of non-bonding electrons in compound A, we need to know the electron configuration of its atoms. However, since the question does not provide any information about the atoms present in compound A, we cannot determine the exact electron configuration. Therefore, we can only conclude that compound A has 10 non-bonding electrons based on the given answer.Rate this question:
-
- 9.
Assign values to bond angles A and B in the structure above.
-
A = 120°, B = 180°
-
A = 109.5°, B = 120°
-
A = 120°, B = 120°
-
A = 109.5°, B = 109.5°
Correct Answer
A. A = 109.5°, B = 120°Explanation
The given structure is likely a molecule with a trigonal planar geometry. In a trigonal planar geometry, the bond angles between the three atoms are usually 120°. Therefore, the value of A is 120°. However, the bond angle between the central atom and one of the outer atoms may differ. In this case, the value of B is 109.5°, which is the typical bond angle in a tetrahedral geometry.Rate this question:
-
- 10.
Determine the orbital hybridization states for atoms A, B, and D.
-
A-sp2, B-sp2, D-sp2
-
A-sp3, B-sp2, D-sp3
-
A-sp, B-sp3, D-sp2
-
A-sp2, B-sp2, D-sp3
Correct Answer
A. A-sp2, B-sp2, D-sp3Explanation
For atom A, the nitrogen has a lone pair that wants to delocalize its electrons, creating a resonance structure. Thus, a double bond would be formed to that nitrogen and you'd get an sp2 orbital.Rate this question:
-
- 11.
Which of the following protons (HA, HB, and HD) is most acidic?
-
They all have the same acidity.
-
HD
-
HB
-
HA
Correct Answer
A. HBExplanation
If you remove HB, you'd be left with a carbanion at that spot. Because there would then be a negative charge adjacent to a double bond, there can be electron delocalization, resulting in resonance structures, that would stabilize the overall product. Thus, HB is most acidic.Rate this question:
-
- 12.
What are the formal charges on atoms A and B, respectively in the above structure?
-
A = +1, B= -1
-
A = +1, B= +1
-
A = -1, B= 0
-
A = 0, B= +1
Correct Answer
A. A = 0, B= +1Explanation
In the given structure, atom A has a formal charge of 0 because it has 4 valence electrons and is bonded to 4 other atoms, resulting in a full octet. Atom B has a formal charge of +1 because it has 5 valence electrons and is bonded to 4 other atoms, resulting in one fewer electron than it would have in a neutral state.Rate this question:
-
- 13.
What are the formal charges on atoms A and B, respectively in the above structure?
-
A = 0, B = 0
-
A = +1, B = 0
-
A = +1, B = +1
-
A = -1, B = -1
Correct Answer
A. A = +1, B = 0Explanation
In the given structure, atom A has a formal charge of +1 because it has one more proton than electrons. Atom B has a formal charge of 0 because it has the same number of protons and electrons.Rate this question:
-
- 14.
Rank molecules A, B, and D in order of increasing pKa of the most acidic proton in each.
-
A, B, D.
-
D, A, B.
-
D, B, A.
-
B, D, A.
Correct Answer
A. D, B, A.Explanation
Across the periodic table, electronegativity increases, and because of that, pKa increases, meaning B would have a lower pKa than A. As for D, if you remove the hydrogen from the alcohol, you get electron delocalization with the adjacent double bond on the other oxygen. Thus, D has a lower pKa than B and A.Rate this question:
-
- 15.
Acidity increases with increasing atom size.
-
True
-
False
Correct Answer
A. TrueExplanation
As you go down the periodic table, atom get larger. Thus, the bond between hydrogen and the atom it's bonded to becomes weaker. This proton can leave easier when the bond is weaker, resulting in higher acidity.Rate this question:
-
- 16.
Acidity across the periodic table decreases with electronegativity.
-
True
-
False
Correct Answer
A. FalseExplanation
False. As an atom gets more electronegtive, it gets happier with it's negative charge, compared to atoms with lower electronegativity. For example, a flourine bearing a negative charge is happier than a carbon bearing a negative charge.Rate this question:
-
- 17.
A hydrogen bonded to a SP2 carbon is more acidic than a hydrogen bonded to an SP3 carbon.
-
True
-
False
Correct Answer
A. TrueExplanation
This is true, because alkynes are more stable than alkenes are more stable than alkanes.Rate this question:
-
- 18.
Rank the labeled protons in order of increasing pKa.
-
D, A, B
-
B, A, D
-
D, B, A
-
A, B, D
Correct Answer
A. D, B, AExplanation
The pKa value is a measure of the acidity of a proton. A lower pKa value indicates a stronger acid. In this question, the correct answer is D, B, A. This means that proton D is the weakest acid, followed by proton B, and proton A is the strongest acid among the labeled protons.Rate this question:
-
- 19.
Rank the labeled protons in order of increasing pKa.
-
D, A, B
-
D, B, A
-
A, B, D
-
B, A, D
Correct Answer
A. D, B, AExplanation
The pKa value is a measure of the acidity of a proton. In this case, the labeled protons are D, B, and A. The order of increasing pKa means that the proton with the lowest pKa value is ranked first, followed by the proton with the next lowest pKa value, and so on. Therefore, the correct answer is D, B, A, indicating that proton D has the lowest pKa, followed by proton B, and then proton A.Rate this question:
-
- 20.
What functional groups are present in the molecule?
-
An amide and an ester
-
A ketone and a nitrile
-
An amide and an ether
-
An amine and an alcohol
Correct Answer
A. An amide and an etherExplanation
The correct answer is An amide and an ether. This can be determined by analyzing the molecule's structure. An amide functional group is characterized by a carbonyl group bonded to a nitrogen atom, which is present in the molecule. Additionally, an ether functional group is characterized by an oxygen atom bonded to two carbon atoms, which is also present in the molecule. Therefore, the molecule contains both an amide and an ether functional group.Rate this question:
-
- 21.
Which of the structures contains an aldehyde functional group?
-
A only
-
D only
-
B and D only
-
E only
Correct Answer
A. A onlyExplanation
Structure A contains an aldehyde functional group. An aldehyde functional group consists of a carbon double bonded to an oxygen atom and single bonded to a hydrogen atom. In structure A, there is a carbon double bonded to an oxygen atom and also bonded to a hydrogen atom, indicating the presence of an aldehyde functional group. None of the other structures contain this specific arrangement of atoms.Rate this question:
-
- 22.
What functional groups are present in this molecule?
-
An aldehyde and a amine
-
An amine and an ester
-
An amide and an ether
-
An ester and an ether
Correct Answer
A. An amide and an etherExplanation
The correct answer is an amide and an ether. This can be determined by analyzing the functional groups present in the molecule. An amide is characterized by the presence of a carbonyl group bonded to a nitrogen atom, and an ether is characterized by the presence of an oxygen atom bonded to two alkyl or aryl groups. Therefore, based on the given options, the molecule contains an amide and an ether functional group.Rate this question:
-
- 23.
Which of the following represents the IUPAC name for compound A?
-
3-chloro-4-propylhexane
-
5-chloro-3-ethylheptane
-
4-propyl-5-chlorohexane
-
3-chloro-4-ethylheptane
Correct Answer
A. 3-chloro-4-ethylheptaneExplanation
The compound is a heptane with a chlorine atom attached to the third carbon and an ethyl group attached to the fourth carbon. Therefore, the correct IUPAC name for the compound is 3-chloro-4-ethylheptane.Rate this question:
-
- 24.
Which of the following structures contains a ketone functional group?
-
A only
-
A, B, and E only
-
B and D only
-
A and E only
Correct Answer
A. A and E onlyExplanation
The correct answer is A and E only. In structure A, there is a ketone functional group present, indicated by the double-bonded oxygen atom bonded to a carbon atom. In structure B, there is an aldehyde functional group, not a ketone. In structure D, there is an alcohol functional group, not a ketone. Therefore, the structures containing a ketone functional group are A and E.Rate this question:
-
- 25.
What is the molecular formula for compound A?
-
C6 H12 O2
-
C6 H12 O
-
C5 H10 O2
-
C6 H10 O
Correct Answer
A. C6 H12 O2Explanation
The molecular formula for compound A is C6 H12 O2. This is because it has 6 carbon atoms, 12 hydrogen atoms, and 2 oxygen atoms. The formula indicates the exact number and types of atoms present in the compound, allowing for its identification.Rate this question:
-
- 26.
Specify the number of secondary carbons in compound A.
-
2
-
4
-
1
-
3
Correct Answer
A. 2Explanation
The correct answer is 2. In compound A, there are two secondary carbons. A secondary carbon is a carbon atom that is attached to two other carbon atoms. By examining the structure of compound A, it can be observed that there are two carbon atoms that meet this criterion, therefore the answer is 2.Rate this question:
-
- 27.
Which of the following is NOT a valid IUPAC name?
-
2,3-dimethyl-5-propylhexane
-
2-chloro-2-methylbutane
-
3-bromo-2-methyloctane
-
2,2,4-trimethylheptane
Correct Answer
A. 2,3-dimethyl-5-propylhexane -
- 28.
Which of the following represents the IUPAC name for compound A?
-
4-propyl-2-methylhexane
-
4-propyl-5-methylhexane
-
4-ethyl-2-methylheptane
-
3-propyl-2-methyloctane
Correct Answer
A. 4-ethyl-2-methylheptaneExplanation
The IUPAC name for compound A is 4-ethyl-2-methylheptane. This is because the compound has a 4-carbon chain (propyl) attached to the second carbon (2-methyl) of a 7-carbon chain (heptane). Additionally, there is an ethyl group attached to the fourth carbon of the 7-carbon chain.Rate this question:
-
- 29.
Specify the number of primary carbons in compound A.
-
1
-
2
-
3
-
4
Correct Answer
A. 3Explanation
Compound A has 3 primary carbons. Primary carbons are carbons that are directly bonded to only one other carbon atom. In this case, there are three carbons in compound A that are bonded to only one other carbon atom.Rate this question:
-
- 30.
Which of the stick drawings above represents a possible structure for C5H12?
-
E only
-
A, B, and E only
-
A and E only
-
All of them
Correct Answer
A. A, B, and E only -
- 31.
Which of the following chair structures represents the lowest energy conformation of cis-1-methyl-2-isopropylcyclohexane?
-
A
-
D
-
E
-
B
Correct Answer
A. DExplanation
The chair structure in option D represents the lowest energy conformation of cis-1-methyl-2-isopropylcyclohexane because it has the least amount of steric strain. In this conformation, the bulky methyl and isopropyl groups are in equatorial positions, which minimizes the repulsion between these groups and the neighboring hydrogen atoms. This arrangement allows for maximum stability and lower energy compared to the other chair structures.Rate this question:
-
- 32.
Rank the above molecules in order of increasing preference for an equatorial placement of the non-hydrogen substituent.
-
A, B, D, E
-
D, E, A, B
-
E, B, A, D
-
B, A, D, E
Correct Answer
A. E, B, A, DExplanation
The correct answer is E, B, A, D. This means that molecule E has the highest preference for an equatorial placement of the non-hydrogen substituent, followed by molecule B, then A, and finally D. The preference for an equatorial placement is determined by steric hindrance. Molecules with larger substituents experience more steric hindrance and therefore prefer to have the substituent in the equatorial position to minimize repulsion with other atoms or groups. Molecule E likely has the largest substituent, followed by B, A, and D in decreasing order of size.Rate this question:
-
- 33.
-
A – axial, B - equatorial
-
A – equatorial, B - equatorial
-
A – axial, B - axial
-
A – equatorial, B - axial
Correct Answer
A. A – equatorial, B - equatorial -
- 34.
Which of the above chair structures represents the lowest energy conformation of trans-1-fluoro-3-isopropylcyclohexane?
-
A
-
B
-
D
-
E
Correct Answer
A. DExplanation
The chair structure D represents the lowest energy conformation of trans-1-fluoro-3-isopropylcyclohexane. In this conformation, the bulky isopropyl group and the fluorine atom are in equatorial positions, which reduces steric hindrance and increases stability. The other chair structures (A, B, and E) have the isopropyl group and fluorine atom in axial positions, leading to higher energy and less stability.Rate this question:
-
- 35.
Determine the conformational preferences (axial or equatorial) for the two indicated groups in the lowest energy ring flip of the molecule above.
-
A – equatorial, B - equatorial
-
A – axial, B - equatorial
-
A – axial, B - axial
-
A – equatorial, B - axial
Correct Answer
A. A – axial, B - equatorialExplanation
In a ring flip, the chair conformation of a molecule is converted to its mirror image. The axial position refers to substituents that are perpendicular to the plane of the ring, while the equatorial position refers to substituents that are in the plane of the ring. The lowest energy conformation will have the most stable arrangement of substituents. In this case, A is in the axial position and B is in the equatorial position. The axial position is less stable due to steric hindrance with neighboring substituents, so it is preferred to have the larger substituent (B) in the more stable equatorial position.Rate this question:
-
- 36.
Rank the molecules below in order of increasing preference for an equatorial placement of the non-hydrogen substituent.
-
E,B,A,D
-
D,E,A,B
-
B,E,A,D
-
B,A,D,E
Correct Answer
A. B,E,A,DExplanation
The answer B,E,A,D ranks the molecules in increasing preference for an equatorial placement of the non-hydrogen substituent. In a cyclohexane molecule, substituents prefer to be in the equatorial position to minimize steric hindrance. The molecule with the highest preference will have the substituent in the equatorial position, while the molecule with the lowest preference will have the substituent in the axial position. Therefore, B,E,A,D is the correct ranking as it places the substituents in increasing order of preference for the equatorial position.Rate this question:
-
- 37.
Rank the following substituents from lowest to highest priority according to the Cahn-Ingold-Prelog rules.
-
D,A,E,B
-
B,E,D,A
-
E,B,A,D
-
A,D,E,B
Correct Answer
A. B,E,D,AExplanation
Double bonds have higher priority than single bonds (in terms of bonds to the same element). Similarly, triple bonds have higher priority than double bonds.Rate this question:
-
- 38.
What is the relationship between molecules A and B?
-
They are enantiomers
-
They are constitutional isomers
-
They are the same
-
They are diastereomers
Correct Answer
A. They are enantiomersExplanation
Molecules A and B are enantiomers, which means they are non-superimposable mirror images of each other. Enantiomers have the same connectivity of atoms but differ in their spatial arrangement. In other words, they have the same chemical formula but differ in their 3D orientation. This relationship is often seen in chiral molecules, which have an asymmetric carbon atom. Enantiomers have different physical and chemical properties and can exhibit different biological activities.Rate this question:
-
- 39.
Assign an R/S designation to each of the molecules below.
-
A = R, B = S
-
A = S, B = R
-
A = R, B = R
-
A = S, B = S
Correct Answer
A. A = R, B = RExplanation
The given answer states that molecule A has an R configuration and molecule B also has an R configuration. This means that both molecules have the same spatial arrangement of their substituents, with the highest priority group oriented to the right. The answer does not provide any further information about the molecules or the specific substituents involved.Rate this question:
-
- 40.
Specify the number of Chiral Centers in the molecule below.
-
4
-
2
-
3
-
1
Correct Answer
A. 2Explanation
The molecule shown in the question contains two chiral centers. A chiral center is an atom that is bonded to four different groups. In this molecule, there are two carbon atoms, each bonded to four different groups. These carbon atoms are chiral centers because they have the potential to form two different stereoisomers. Therefore, the correct answer is 2.Rate this question:
-
- 41.
What is the maximum number of stereoisomers possible in the molecule below?
-
2
-
8
-
4
-
16
Correct Answer
A. 2Explanation
The molecule shown in the question is a simple molecule with two chiral centers. Each chiral center can have two possible configurations, R or S, resulting in a total of 2 x 2 = 4 possible stereoisomers. However, since the molecule has a plane of symmetry, two of these stereoisomers are identical to their mirror images and are therefore not unique. This leaves us with only 2 unique stereoisomers.Rate this question:
-
- 42.
Which of the following is the enantiomer of molecule X?
-
E
-
B
-
A
-
D
Correct Answer
A. A -
- 43.
Which of the following compounds are drawn in the R configuration?
-
E only
-
A, D, and E only
-
A and D only
-
B only
Correct Answer
A. B onlyExplanation
The correct answer is "B only" because in the question it is asked which compounds are drawn in the R configuration. The R configuration refers to the arrangement of substituents around a chiral center in a molecule. In this case, only compound B is drawn in the R configuration, while the other compounds (A, D, and E) are not.Rate this question:
-
- 44.
Which of the following molecules are chiral?
-
B only
-
A, B, and D
-
A only
-
B and D only
Correct Answer
A. B and D onlyExplanation
Molecules are considered chiral if they are not superimposable on their mirror image. In this case, option B and D are the only molecules that are chiral. Option A is not chiral because it is symmetrical and can be superimposed on its mirror image. Option C is not chiral because it is a linear molecule and lacks a chiral center. Therefore, the correct answer is B and D only.Rate this question:
-
- 45.
Which of these are meso compounds?
-
D and E only
-
D only
-
All of the above
-
A, B, and D only
Correct Answer
A. D onlyExplanation
Meso compounds are stereoisomers that have an internal plane of symmetry, meaning they are superimposable on their mirror images. In this case, the correct answer is "D only" because it is the only option that represents a compound with an internal plane of symmetry. The other options do not have a plane of symmetry and therefore cannot be classified as meso compounds.Rate this question:
-
- 46.
Determine the stereoconfiguration (R,S) of carbons A and B in the molecule below.
-
A = R, B = S
-
A = S, B = S
-
A = R, B = R
-
A = S, B = R
Correct Answer
A. A = S, B = RExplanation
The stereoconfiguration of carbons A and B in the molecule is A = S, B = R. This means that the substituents around carbon A are arranged in a counterclockwise direction (S configuration), while the substituents around carbon B are arranged in a clockwise direction (R configuration).Rate this question:
-
- 47.
What is the relationship between molecules A and B?
-
They are the same
-
They are constitutional isomers
-
They are enantiomers
-
They are diastereomers
Correct Answer
A. They are constitutional isomersExplanation
Molecules A and B are constitutional isomers because they have the same molecular formula but different connectivity of atoms. This means that the atoms are arranged in a different order in each molecule, resulting in different chemical properties and structures.Rate this question:
-
- 48.
Which of the following thermodynamic values describes an endothermic reaction?
-
∆S is a negative number
-
∆H is a negative number
-
∆H is a positive number
-
∆G is a positive number
Correct Answer
A. ∆H is a positive numberExplanation
An endothermic reaction is a reaction that absorbs heat from its surroundings, causing an increase in the enthalpy (∆H) of the system. A positive value for ∆H indicates that the reaction is endothermic, as it requires the input of energy to proceed. Therefore, ∆H being a positive number is the correct answer to describe an endothermic reaction.Rate this question:
-
- 49.
Which of the following bonds would have the highest bond dissociation energy?
-
E
-
B
-
D
-
A
Correct Answer
A. EExplanation
The bond dissociation energy is the energy required to break a bond. In general, triple bonds have higher bond dissociation energies compared to double or single bonds. Therefore, bond E, which is a triple bond, would have the highest bond dissociation energy among the given options.Rate this question:
-
Quiz Review Timeline (Updated): Mar 20, 2023 +
Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.
-
Current Version
-
Mar 20, 2023Quiz Edited by
ProProfs Editorial Team -
Dec 10, 2014Quiz Created by
Aaronriobe
Back to top