Question 1

Which of the following is true about the base peak in mass spectrometry?

Accepted Answer

A) The m/z value equals the molecular weight of the compound. 
B) The m/z value corresponds to a very stable carbanion. 
C) It has the largest peak height in the spectrum. 
D) It has the highest m/z value of all the peaks in the spectrum. 
E) The base peak is assigned a relative abundance equal to that of the parent ion. 
A) The m/z value equals the molecular weight of the compound. 
B) The m/z value corresponds to a very stable carbanion. 
C) It has the largest peak height in the spectrum. 
D) It has the highest m/z value of all the peaks in the spectrum. 
E) The base peak is assigned a relative abundance equal to that of the parent ion.

Question 2

Which of the following regions of the electromagnetic spectrum has the greatest energy per photon?

Accepted Answer

A) visible 
B) microwave 
C) radio 
D) ultraviolet 
E) infrared 
A) visible 
B) microwave 
C) radio 
D) ultraviolet 
E) infrared

Question 3

What m/z value would you predict for the most stable fragment peak in the mass spectrum of 4-ethylheptane?

Accepted Answer

A) 128 
B) 127 
C) 113 
D) 99 
E) 85 
A) 128 
B) 127 
C) 113 
D) 99 
E) 85

Question 4

Identify the compound that has a formula of C5H10 and bending vibrations at 990 and 910 cm-1.

Accepted Answer

A) 1-pentene 
B) cis-2-pentene 
C) trans-2-pentene 
D) 2-methyl-1-butene 
E) 2-methyl-2-butene 
A) 1-pentene 
B) cis-2-pentene 
C) trans-2-pentene 
D) 2-methyl-1-butene 
E) 2-methyl-2-butene

Question 5

2-Methylhexane shows an intense peak in the mass spectrum at m/z = 43.Propose a likely structure for this fragment.

Accepted Answer

The answer of 2-Methylhexane shows an intense peak in the...

Question 6

In IR spectroscopy,the intensity of a peak is dependent on

Accepted Answer

A) the strength of the bond. 
B) the mass of atoms. 
C) the polarity of the bond. 
D) temperature of the room. 
E) none of the above. 
A) the strength of the bond. 
B) the mass of atoms. 
C) the polarity of the bond. 
D) temperature of the room. 
E) none of the above.

Question 7

Which molecule below has two significant bands in the IR at 2720 cm-1 and 2820 cm-1 (medium)?

Accepted Answer

A) CH3COCH2CH 
B) CH3CH2CO2CH3 
C) CH2     CHCH2CH3 
D) CH3CH2CH2CHO 
E) CH3CH2CH2OH 
A) CH3COCH2CH 
B) CH3CH2CO2CH3 
C) CH2     CHCH2CH3 
D) CH3CH2CH2CHO 
E) CH3CH2CH2OH

Question 8

Which of the following compounds exhibits the highest λmax in UV spectra?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 9

Which of the following compounds absorbs the longest wavelength of UV-visible light?

Accepted Answer

A) (
E) -2-butene 
B) (Z)-2-butene 
C) 1-hexene 
D) (Z)-1,3-hexadiene 
E) (
E) -1,3,5-hexatriene 
A) (
E) -2-butene 
B) (Z)-2-butene 
C) 1-hexene 
D) (Z)-1,3-hexadiene 
E) (
E) -1,3,5-hexatriene

Question 10

Which of the following normally occurs in a molecule when a photon of infrared light is absorbed?

Accepted Answer

A) An electron moves to an orbital of higher potential energy. 
B) A transition between allowed vibrational energy states occurs. 
C) An electron changes alignment in a magnetic field. 
D) The molecule gains an electron. 
E) The molecule loses an electron. 
A) An electron moves to an orbital of higher potential energy. 
B) A transition between allowed vibrational energy states occurs. 
C) An electron changes alignment in a magnetic field. 
D) The molecule gains an electron. 
E) The molecule loses an electron.

Question 11

In IR spectroscopy,which of the following bonds will produce the most intense peak?

Accepted Answer

A) C-C 
B) C   C 
C) C   O 
D) C   N 
E) C-H 
A) C-C 
B) C   C 
C) C   O 
D) C   N 
E) C-H

Question 12

Which compound would be expected to show intense IR absorption at 2710 and 1705 cm-1?

Accepted Answer

A) CH3COCH2CH3 
B) PhCOCH3 
C) PhCHO 
D) CH2     CHCOCH3 
A) CH3COCH2CH3 
B) PhCOCH3 
C) PhCHO 
D) CH2     CHCOCH3

Question 13

How can UV spectroscopy be used to estimate the nucleotide composition of DNA?

Accepted Answer

The melting temperature of DNA

Question 14

An increase in conjugation is correlated with ________ in the energy of the LUMO,________ in the energy of the HOMO,and ________ in lmax.

Accepted Answer

A) a decrease,an increase,a decrease 
B) a decrease,an increase,an increase 
C) an increase,a decrease,a decrease 
D) an increase,a decrease,an increase 
E) an increase,an increase,a decrease 
A) a decrease,an increase,a decrease 
B) a decrease,an increase,an increase 
C) an increase,a decrease,a decrease 
D) an increase,a decrease,an increase 
E) an increase,an increase,a decrease

Question 15

Which of the following is not a major peak in the MS of isopentane?

Accepted Answer

A) 29 
B) 43 
C) 57 
D) 60 
E) 72 
A) 29 
B) 43 
C) 57 
D) 60 
E) 72

Question 16

Which molecule below has a significant band in the 1720 - 1780 cm-1 range of its IR spectrum?

Accepted Answer

A) CH3CH2CH2OH 
B) CH3C   CCH2CH3 
C) CH3CH2CH(NH2)CH3 
D) (CH3)3N 
E) CH3CO2CH2CH3 
A) CH3CH2CH2OH 
B) CH3C   CCH2CH3 
C) CH3CH2CH(NH2)CH3 
D) (CH3)3N 
E) CH3CO2CH2CH3

Question 17

Ethyl acetate has the structure CH3CO2CH2CH3.Which set of m/z peaks is most consistent with this structure?

Accepted Answer

A) 88,73,43 
B) 88,76,45 
C) 88,73,45 
D) 88,76,43 
E) 88,72,70,44 
A) 88,73,43 
B) 88,76,45 
C) 88,73,45 
D) 88,76,43 
E) 88,72,70,44

Question 18

Which of the following species has a characteristic absorption at 2200 cm-1 in its IR spectrum?

Accepted Answer

A) PhCH2CN 
B) PhCH2N(CH3)2 
C) PhCH2CO2CH3 
D) PhCH2CH2OH 
E) PhCH2OCH3 
A) PhCH2CN 
B) PhCH2N(CH3)2 
C) PhCH2CO2CH3 
D) PhCH2CH2OH 
E) PhCH2OCH3

Question 19

Which of the following carbonyl groups exhibits the highest wavenumber in infrared spectroscopy?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 20

Give the ion that corresponds to a m/z ratio of 56 in a mass spectrum of 1-butanol.

Accepted Answer

A)    
B)    
C)    
D)    
E) none of the above 
A)    
B)    
C)    
D)    
E) none of the above

Exam 13: Mass Spectrometry,infrared Spectroscopy,and Uvvis Spectroscopy

Which of the following is true about the base peak in mass spectrometry?

Which of the following regions of the electromagnetic spectrum has the greatest energy per photon?

What m/z value would you predict for the most stable fragment peak in the mass spectrum of 4-ethylheptane?

Identify the compound that has a formula of C5H10 and bending vibrations at 990 and 910 cm-1.

2-Methylhexane shows an intense peak in the mass spectrum at m/z = 43.Propose a likely structure for this fragment.

In IR spectroscopy,the intensity of a peak is dependent on

Which molecule below has two significant bands in the IR at 2720 cm-1 and 2820 cm-1 (medium)?

Which of the following compounds exhibits the highest λmax in UV spectra?

Which of the following compounds absorbs the longest wavelength of UV-visible light?

Which of the following normally occurs in a molecule when a photon of infrared light is absorbed?

In IR spectroscopy,which of the following bonds will produce the most intense peak?

Which compound would be expected to show intense IR absorption at 2710 and 1705 cm-1?

How can UV spectroscopy be used to estimate the nucleotide composition of DNA?

An increase in conjugation is correlated with ________ in the energy of the LUMO,________ in the energy of the HOMO,and ________ in lmax.

Which of the following is not a major peak in the MS of isopentane?

Which molecule below has a significant band in the 1720 - 1780 cm-1 range of its IR spectrum?

Ethyl acetate has the structure CH3CO2CH2CH3.Which set of m/z peaks is most consistent with this structure?

Which of the following species has a characteristic absorption at 2200 cm-1 in its IR spectrum?

Which of the following carbonyl groups exhibits the highest wavenumber in infrared spectroscopy?

Give the ion that corresponds to a m/z ratio of 56 in a mass spectrum of 1-butanol.

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds: Nomenclature, physical Properties, and Structure

Isomers: the Arrangement of Atoms in Space

Alkenes: Structure,nomenclature,and an Introduction to Reactivity - Thermodynamics and Kinetics

The Reactions of Alkenes - the Stereochemistry of Addition Reactions

The Reactions of Alkynes - Introduction to Multistep Synthesis

Delocalized Electrons: Their Effect on Stability, pka, and the Products of a Reaction - Aromaticity and Electronic Effects: an Introduction to the Reactions of Benzene

Substitution and Elimination Reactions of Alkyl Halides

Reactions of Alcohols, ethers, epoxides, amines and Sulfur-Containing Compounds

Organometallic Compounds

Radicals

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Α-Carbon

Reactions of Benzene and Substituted Benzenes

More About Amines - Reactions of Heterocylic Compounds

The Organic Chemistry of Carbohydrates

Amino Acids,peptides,and Proteins

Catalysis in Organic Reactions and in Enzymatic Reactions

The Organic Chemistry of the Coenzymes, compounds Derived From Vitamins

The Organic Chemistry of the Metabolic Pathways

The Organic Chemistry of Lipids

The Chemistry of the Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

Filters

Identify the compound that has a formula of C₅H₁₀ and bending vibrations at 990 and 910 cm^-1.

Which molecule below has two significant bands in the IR at 2720 cm^-1 and 2820 cm^-1(medium)?

Which of the following compounds exhibits the highest λ_max in UV spectra?

Which compound would be expected to show intense IR absorption at 2710 and 1705 cm^-1?

An increase in conjugation is correlated with in the energy of the LUMO, in the energy of the HOMO,and in l_max.

Which molecule below has a significant band in the 1720 - 1780 cm^-1 range of its IR spectrum?

Ethyl acetate has the structure CH₃CO₂CH₂CH₃.Which set of m/z peaks is most consistent with this structure?

Which of the following species has a characteristic absorption at 2200 cm^-1 in its IR spectrum?