CÂU HỎI TRẮC NGHIỆM TIẾNG ANH (CÓ ĐÁP ÁN)

CÂU HỎI TRẮC NGHIỆM, TIẾNG ANH CÓ ĐÁP ÁN

CÂU HỎI TRẮC NGHIỆM (CÓ ĐÁP ÁN)

PHAN ĐỨC TOÀN Câu 1: Which of the following is not a true statement?

A The operating frequency of an NMR spectrometer depends on the strength of the magnet

B All protons in a compound experience the same shielding

C The radiation used in NMR spectroscopy is rf radiation

D The effective magnetic field is the magnetic field the proton senses

E The energy difference between the alpha and beta spin states depends on the strength of the applied magnetic field

Câu 2: How many kinds of chemically nonequivalent hydrogen nuclei are there in

ethylbenzene?

A 3 B 4 C 5 D 6 E 7

Câu 3: Since the chemical shift is defined as the ratio of the “distance downfield from a

standard in [Hz]” and the “operating frequency of the spectrometer in [MHz],” what units does chemical shift have?

A MHz (megahertz) B KHz (kilohertz) C ppm (parts per million)

D Hz (hertz) E unitless

Câu 4: In what region of the 1H NMR spectrum would you find the signal for the acidic hydrogen of a carboxylic acid?

A 0–2.5 ppm B 2.5–5 ppm C 5–7.5 ppm D 7.5–10 ppm E 10–12 ppm

Câu 5: What is the multiplicity of the methylene hydrogens of a carbon that is attached to a

methyl group and to a methoxy group?

A singlet B quintet C quartet D triplet E doublet

Câu 6: Which signal of C6H5-C(=O)-CH(CH3)2 has the greatest integrated signal area?

A It is the aromatic protons that are a singlet

B It is the methyl signal that is a triplet

C It is the methyl signal that is a doublet

D It is the methylene signal that is a multiplet

E It is the methine signal that is a septet

Câu 7: The four peaks in a quartet occur at chemical shifts a, a + x, a + 2x, and a + 3x (with

intensities 1:3:3:1) Under what condition do the four peaks of a doublet of doublets (a is coupled to b and to c) also occur at chemical shifts a, a + x, a + 2x, and a + 3x (with intensities

A a sharp singlet B two singlets with equal intensity C a broad singlet

D two singlets with different intensities E a doublet

Câu 9: The 1H NMR spectrum of which of the following compounds is altered significantly upon addition of a few drops of D2O to the NMR sample?

A methyl ethyl ether B propanol C propanone

D methyl acetate E acetonitrile

Câu 10: What does the bottom-most spectrum of a DEPT 13C NMR spectrum show?

A It is a signal for each carbon

B It is a signal for each carbon that is covalently bonded to hydrogen(s)

C It is a signal for each methyl carbon

D It is a signal for each methylene carbon

E It is a signal for each carbon that is covalently bonded to a methyl group

Câu 11: Each of the following compounds has a singlet in its 1H NMR spectrum Which compound would have its singlet at the highest frequency (farthest downfield)?

A 1-bromo-2,2-dimethylpropane B ethyl methyl ether C 2-ethoxy-2-methylbutane

D 1,2-dibromoethane E ethyl-tert-butyl ether

Câu 12: Which of the following compounds would have the signal for its methylene hydrogens

farthest downfield?

A ethyl chloride B ethyl iodide C ethanol

D ethyl bromide E ethyl fluoride

Câu 13: How many signals would you expect to see for 1,3-dinitrobenzene in its H NMR and

13

C NMR spectra?

A four in its 1H NMR spectrum and three in its 13C NMR spectrum

B two in its 1H NMR spectrum and three in its 13C NMR spectrum

C three in its 1H NMR spectrum and three in its 13C NMR spectrum

D three in its 1H NMR spectrum and four in its 13C NMR spectrum

E four in its 1H NMR spectrum and four in its 13C NMR spectrum

Câu 14: The 1H NMR spectrum of methyl propyl ketone has what?

A 3 signals: a singlet, a triplet, and a quarte B 3 signals: 2 triplets, and a multiplet

C 3 signals: 2 triplets, and a quartet D 4 signals: a singlet, 2 triplets, and a multiplet

E 4 signals: a singlet, 2 triplets, and a quartet

Câu 15: The different kinds of protons in 3-chloro-3-methylpentane have an integral ratio of

(looking left to right across the spectrum) what?

A 5:3 B 4:3:6 C 2:3:3 D 4:6:3 E 4:9

Câu 16: A single hydrogen bonded to a carbon is called what?

A a methyl hydrogen B an isolated hydrogen C a methylene hydrogen

D a single hydrogen E a methine hydrogen

Câu 17: Which hydrogens in CH3CH2-C(=O)-CH2CH(CH3)2 are the most shielded?

A the methyl hydrogens of the isobutyl group B the methine hydrogen

C the methylene hydrogens of the carbon bonded to oxygen

D the methylene hydrogens of the carbon bonded to C=O

E the methyl hydrogens of the ethyl group

Câu 18: How many signals would you expect to see for 1,2-dinitrobenzene in its 1H NMR and

13

C NMR spectra?

A one in its 1H NMR spectrum and three in its 13C NMR spectrum

B two in its 1H NMR spectrum and two in its 13C NMR spectrum

C three in its 1H NMR spectrum and three in its 13C NMR spectrum

D three in its 1H NMR spectrum and two in its 13C NMR spectrum

E two in its 1H NMR spectrum and three in its 13C NMR spectrum

Câu 19: How many signals would be present in the C NMR spectrum of methyl propyl ketone?

A 3 B 4 C 5 D 6 E 7

Câu 20: Which of the following is not a true statement?

A Signals occurring at low frequencies have small ppm values

B The chemical shift is independent of the operating frequency of the NMR spectrometer

C The splitting of a signal is determined by the number of equivalent hydrogens bonded to an adjacent carbon

D The number of peaks in a signal is called the multiplicity of the signal

E Equivalent protons split one another

Câu 21: Which set of protons in 1-chloropentane are the most shielded?

A the hydrogens on C-5 B the hydrogens on C-3 C the hydrogens on C-2

D the hydrogens on C-1 E the hydrogens on C-4

Câu 22: How many signals would you expect to see in the 1H NMR spectrum of chlorocyclobutane?

Câu 24: Which compound has its signal farthest upfield?

A methyl fluoride B methyl chloride C methyl bromide D methyl iodide E methanol

Câu 25: Which of the following is the correct ratio of the peak intensities of a quartet?

A 1:3:3:1 B 1:1:1:1 C 1:2:2:1 D 1:1:2:2 E 1:4:4:1

Câu 26: Which set of hydrogens in vinyl chloride has the smallest coupling constant?

A the trans hydrogens B the hydrogens on C-2 C the cis hydrogens

Câu 27: Which of the following compounds will show an H NMR spectrum with 2 doublets, a triplet, and a quartet?

A CH3CHCl-C(=O)-CH2-CH(=O) B CH3CH2-C(=O)-OCH2CH3

C CH3CH2CH2-CH(= D CH3-C(=O)-CH2CH2CH3 E (CH3)2CH-C(=O)-CH2CH3

Câu 28: What is the multiplicity of the OH group of an alcohol in a solution that contains a trace

amount of acid?

A quartet B doublet C triplet D singlet E quintet

Câu 29: What causes the splitting in a spin-coupled 13C NMR spectrum?

A. 1H–1H spin–spin coupling B. 13C–1H spin–spin coupling

C. 13C–12C spin–spin coupling D. 13C–13C spin–spin coupling

E none of the above, since no splitting is observed

Câu 30: How many signals would you expect to see in the 1H NMR spectrum of butane?

A 1 B 2 C 3 D 4 E 5

Câu 31: How many signals would you expect to see for 1,4-dinitrobenzene in its 1H NMR and

13

C NMR spectra?

A two in its 1H NMR and two in its 13C NMR spectra

B one in its 1H NMR and one in its 13C NMR spectra

C one in its 1H NMR and two in its 13C NMR spectra

D two in its 1H NMR and one in its 13C NMR spectra

E two in its 1H NMR and three in its 13C NMR spectra

Câu 32: Which of the following will occur farthest downfield?

A the hydrogens of ethene B the hydrogens of dimethyl ether

C the hydrogens of H-C(=O)-H D the hydrogens of ethyne

E the hydrogens of benzene

Câu 33: How can CH3CH2-C(=O)-OCH3 and CH3-C(=O)-OCH2CH3 be distinguished by 1H NMR?

A They have different numbers of signals

B Only CH-C(=O)-OCH CH will have a singlet, a triplet, and a quartet

C The signals for each compound will have different multiplicities

D Only CH3CH2-C(=O)-OCH3 will have a singlet, a triplet, and a quartet

E It is by the multiplicity of the signal appearing farthest downfield

Câu 34: How many signals will vinyl chloride have in its 1H NMR spectrum?

A 1 B 2 C 3 D 4 E 5

Câu 35: Which of the following compounds show(s) three signals in its 1H NMR spectrum?

A a: 1-chloro-3-methylbutane B b: 2-chloro-2-methylbutane

C c: 2-chloropentane D d: 3-chloropentane E b and d

Câu 36: How many signals does 2,2,4-trimethylpentane have in its 1H NMR spectrum?

A 2 B 3 C 4 D 5 E 6

Câu 37: Why does the signal for the hydrogen bonded to oxygen in ethanol appear as a triplet in

pure ethanol and as a singlet in ethanol that contains a trace amount of acid?

A Photon exchange cause spin decoupling

B Spin exchange causes spin decoupling

C Chemical exchange causes spin decoupling

D Electron exchange causes spin coupling

E Hydrogen exchange causes more spin coupling

Câu 38: In the 1H NMR spectrum of CH3CH2Cl, the quartet for the CH2 group has a coupling constant of 7 Hz What is the coupling constant for the CH3 triplet?

A 0 B 3,5 C 7 D 10,5 E 14

Câu 39: Which of the following is not a true statement?

A There are more hertz/ppm on a 360-MHz NMR than on a 60-MHz NMR

B The chemical shift in hertz is independent of the operating frequency of the NMR

C Coupling constants do not depend on the operating frequency of the NMR

D "Clean" splitting patterns require the chemical shift difference between peaks to be at least 10 times the coupling constant

E Spectra taken at higher operating frequency have higher resolution

Câu 40: In the DEPT C spectrum of 1,3-diethylbenzene, how many peaks would be observed

in the second spectrum from the bottom?

A 0 B 1 C 2 D 3 E 4

Câu 41: Which of the following is not a true statement?

A Signals occurring at low frequencies will have small chemical shift values

B If "a" is more shielded than "b," "a" will appear farther upfield than "b."

C Downfield is to the left in an 1H NMR spectrum

D If "a" is less shielded than "b," "a" will require a greater frequency than "b."

E The chemical shift of a hydrogen will vary with the operating frequency of the NMR spectrometer

Câu 42: What would be the multiplicity of the methylene group in CH3CH2-C(=O)-CH(CH3)2?

A a singlet B a quartet C a doublet D a doublet of doublets E a triplet

Câu 43: How many signals would you expect to see in the 1H NMR spectrum of bromopropane and 2-bromopropane?

1-A 1-Bromopropane has 3 and 2-bromopropane has 2

B 1-Bromopropane has 4 and 2-bromopropane has 4

C 1-Bromopropane has 2 and 2-bromopropane has 3

D 1-Bromopropane has 3 and 2-bromopropane has 4

E 1-Bromopropane has 3 and 2-bromopropane has 3

Câu 44: How many signals would you expect to see in the 1H NMR spectrum of methylpropene?

Câu 47: In what region of the H NMR spectrum would you expect to find signals that are due

C 1,2-dibromobutane D 1,4-dibromobutane E 1,2-dibromo-2-methylpropane

Câu 49: What multiplicity would you expect for the signal of a proton bonded to a carbon that is

adjacent to two chemically equivalent methyl groups?

A a quintet B a sextet C a triplet D a quartet E a septet

Câu 50: Which of the following describes the 1H NMR spectrum of 1,2-dichloroethane?

A one doublet of doublets B one doublet C one singlet

D two doublets E two triplets

Câu 51: How many lines are there in a doublet of doublets if the two coupling constants are the

same?

A 2 B 3 C 4 D 5 E 6

Câu 52: The coupling constant between the geminal hydrogens in trans-3-chloropropenoic acid

is 14 Hz in an NMR spectrum that was recorded on a 60-MHz spectrometer What would be the coupling constant if the spectrum were measured on a 600-MHz spectrometer?

A a singlet B a doublet C a quintet D a triplet E a quartet

Câu 55: In what region of a 13C NMR spectrum would you find a carbon in an aromatic ring?

A 30–40 ppm B 8–35 ppm C 110–170 ppm D 165–175 ppm E 205–220 ppm

Câu 56: The chemical shift is calculated using which of the following equations?

A δ = distance downfield from TMS (Hz)/operating frequency of the spectrometer (MHz)

B δ = distance downfield from TMS(Hz)/magnet strength of the spectrometer

C δ = distance upfield from TMS (Hz)/operating frequency of the spectrometer (MHz)

D δ = operating frequency of the spectrometer (MHz)/distance downfield from TMS (Hz)

E δ = distance downfield from TMS (Hz) X operating frequency of the spectrometer (MHz)

Câu 57: In the 1H NMR spectrum of a compound with molecular formula C5H10O, the integrated peak areas were: 5.4, 3.6, 3.6, and 5.4 What is the ratio of protons in the four peaks?

A 3:2:2:3 B 5:4:4:5 C 3:3:2:2 D 9.7:6.5:6.5:9.7

Câu 58: What is the ratio of peak intensities in a clean triplet?

A 1:3:1 B 2:1:2 C 1:2:1 D 3:1:3 E 1:1:1

Câu 59: What condition is required in order for signals to have "clean" splitting patterns?

A. The difference in the chemical shifts of two adjacent protons must be < 10 J.

B. The difference in the chemical shifts of two adjacent protons must be > 10 J.

C. The difference in the chemical shifts of two adjacent protons must be < J.

D. The difference in the chemical shifts of two adjacent protons must be = J.

E. The difference in the chemical shifts of two adjacent protons must be > J.

Câu 60: Which of the following has the greatest value for its chemical shift in a 13C NMR spectrum?

A. the alpha carbon of an alkyl halide

B. a carbonyl carbon

C. the alpha carbon of an alcohol

D. a carbon of TMS

E. the carbon of a benzene ring

Câu 61: Why is the signal for the C-2 hydrogen of 2-chloro-3-methylbutane the one that appears farthest downfield?

A It is the hydrogen in the middle of the compound.

B. It is the most shielded hydrogen.

C. It is closest to the electron-donating chloro substituent.

D. It has no equivalent hydrogens.

E. It is closest to the electron-withdrawing chloro substituent.

Câu 62: What is the multiplicity of the CH 2 hydrogens in CH 3 OCH 2 CH 2 OCH 3 ?

A. a triplet B. a singlet C. a doublet D. a doublet of doublets E. a quartet

Câu 63: What would the 1H NMR spectrum of 1,3-cyclohexadiene look like?

A 3 signals: a triplet, a multiplet, and a doublet

B. 3 signals: two doublets and a multiplet

C. 3 signals: a singlet, a multiplet, and a doublet

D. 3 signals: a doublet and two triplets

E. 3 signals: a triplet, a multiplet, and a doublet of doublets

Câu 64: Which of the following is not a true statement?

A. A C-2 hydrogen of 1-chlorobutane shows a signal farther downfield than a signal for a C-1 hydrogen.

B. Protons that are deshielded require a higher frequency to sense the effective magnetic field.

C. Dimethyl ketone shows two signals in its 13C NMR spectrum.

D. Deshielded protons are located farther downfield in an NMR spectrum.

E. Diethyl ketone shows two signals in its 1H NMR spectrum.

Câu 65: Which of the following describes the 1H NMR spectrum of CH 3 CH 2 -CH(=O)?

A two triplets and a multiplet

B a singlet, a triplet, and a quartet

C two doublets and a triplet

D. a singlet, a doublet, and a quartet

E. a singlet, a triplet, and a doublet of doublets

Câu 66: Which of the following is true?

A a: More shielded protons require a lower frequency to come into resonance.

B. b: Protons in electron-rich environments are less shielded.

C. c: B(effective) = B(applied) – B(local)

D. d: Electron-withdrawing groups shield neighboring atoms.

E. It is the protons on C-4.

Câu 68: What would the 1H NMR spectrum of nitrobenzene, C 6 H 5 -NO 2 , look like?

A It would have 1 unsplit signal. B. It would have 3 signals: a doublet and 2 triplets.

C. It would have 3 signals: a doublet, a doublet of doublets, and a triplet.

D. It would have 3 signals: 2 doublets and a triplet.

E. It would have 2 signals: a doublet and a triplet.

Câu 69: How many signals would you expect to see in the 1H NMR spectrum of

A the hydrogens of the methylene group

B. the hydrogens of the methyl group bonded to the oxygen

C the hydrogens on the benzene ring adjacent to the ether group

D. the hydrogens on the benzene ring adjacent to the methyl group

E. the hydrogens of the methyl group bonded to the benzene ring

Câu 72: Identify the compound with molecular formula C 9 H 12 that has a triplet at 1.21 ppm (3H), a singlet at 2.30 ppm (3H), a quartet at 2.60 ppm (2H), and a singlet at 7.04 ppm (4H).

A. 1,2,4-trimethylbenzene B. isopropylbenzene C 1,3,5-trimethylbenzene

D 1-ethyl-4-methylbenzene E. propylbenzene

Câu 73: What would be the splitting of the protons on the CH 2 groups of butane?

A triplet of quartets B triplet C single D sextet E doublet

Câu 74: Which of the following is the correct order for the coupling constants of vinyl protons?

A trans > cis > geminal > long range B. geminal > long range > cis > trans

C. cis > trans > geminal > long range D. trans > long range > cis > geminal

E. trans > geminal > cis > long range

Câu 75: NMR relies on?

A the absorption of energy by chemical bonds

B the absorption of energy by chemical bonds in conjugated p systems

C the absorption of energy by the nucleus of any atom

D the absorption of energy by the nucleus of some atoms

E the absorption of energy by the nucleus of some atoms, exciting their spin state

Câu 76: Which of the following statements about shielding is false?

A shielding is an increased effect of the external magnetic field due to the induced magnetic field in the molecule

B shielding is a decreased effect of the external magnetic field due to the induced magnetic field

in the molecule

C shielding determines the chemical shift of the atom

D the standard reference for measuring shielding effects is TMS

E deshielding shifts the signal or peak downfield

Câu 77: Electronegative atoms?

A shield adjacent protons shifting the peak upfield

B deshield adjacent protons shifting the peak downfield

Câu 78: Alkenes and arenes protons are?

A shielded due to the induced magnetic field of the p electrons

B deshielded due to the induced magnetic field of the p electrons

Câu 79: Which of the following statements about proton NMR is false?

A the number of peaks indicates the number of hydrogen atoms

B the multiplicity (or splitting pattern) indicates the number of vicinal protons

C the chemical shift indicates the local chemical environment (i.e the presence of electronegative atoms and/or p bonds)

D the intensity, or area, of the peak indicates the number of each type of proton

E the number of peaks indicates the number of chemically distinct protons