Test: Spectroscopy Level - 2 - Chemistry MCQ

Of the mo lecules CH₄, CO₂, benzene and H₂, the ones that will absorb infrared radiation are:

Which one of the normal modes of ethylene is active in the infrared:

The vibrational stretching frequency of N₂ can be determined using:

The number of IR active vibrational modes in ammonia is:

The number of vibrational degree of freedom in a gaseous mixture of ³⁵Cl₂O, ³⁷Cl₂O, and ³⁵Cl, ³⁷ClO is:

IR stretching frequencies of carbonyl groups in aldehydes and acid chlorides in cm^–1 are:

Which among the following exhibits a carbonyl absorption band at 1770 cm^–1:

Which one of the following exhibits rotational spectra:

The bond that gives the most intense band in the infrared spectrum for its stretching vibrations is:

An examinations of saturated hydrocarbons containing methyl group show asymmetrical (V_as) and symmetrical (V_s) stretching modes in the region of:

¹³C NMR spectrum of DMSO-d₆ gives a signal at δ 39.7 ppm as a:

The molecule with the smallest rotational constant (in the microwave spectrum) among the following is:

Of the vibrational modes given below, the IR active mode(s) is (are):

Which of the fo llowing statements is/are true:

(I) HCl absorbs IR radiat ion
(II) CO₂ absorbs IR radiat ion
(III) H atom absorbs IR radiation
(IV) H atom absorbs UV- vis and microwave radiation

N₂ does not show pure vibrat ional spectral because:

How many normal modes does the CO₂ molecule have; What if the C and the O atoms were constrained to move in one dimensional:

¹H NMR spectrum of a mixture of benzene and acetonitrile shows two singlets of equal integration. The molar ratio of benzene: acetonitrile is:

The absorption at λ_max 279 nm (ε = 15) in the UV spectrum of acetone is due to:

¹H NMR spectrum of an organic compound recorded on a 500 MHz spectrometer showed a quartet with line positions at 1759, 1753, 1747, 1741 Hz. Chemical shift and coupling constant (Hz) of the quartet are:

The correct statement in the context of NMR spectroscopy is:

The reaction between PI₃, PSCl₃ and zinc powder gives P₃I₅ as one of the products. The solution state ³¹P NMR spectrum of P₃I₅ shows a doublet and a triplet . The correct structure of P₃I₅ is:

The compound that exhibits following spectral data is:

¹H NMR: (d, J = 12.3 Hz, 1H), 7.7 (d, J = 8.0 Hz, 2H), 6.8 (d, J = 8.0 Hz, 2H), 5.8 (d, J = 12.3 Hz, 1H), 3.8 (s, 3H), 3.0 (s, 6H) ppm

Number of signals present in the proton decoupled ¹³C NMR spectrum of the following compound is:

The structure of the compound having the following characteristics spectral data, is IR: 1690 cm^–1.

¹H-NMR: 1.30 (3H, t, J = 7.2 Hz); 2.41 (2H, q, J = 7.2 Hz); 2.32 (3H, s); 7.44 (1H, t, J = 7.0 Hz); 7.57 (1H, dt, J = 7.0, J = 7.0, 3.0 Hz); 7.77 (1H, t, J = 3.0 Hz); 7.90 (1H, dt, J = 7.0, 3.0 Hz); EI mass: m/z 119 (100%); 57 (80%)

NMR spectroscopy can be used to assay for drug binding to certain protein targets. One of the primary objective of any binding assay is the quantification of the free and the bound forms of a drug molecule at a certain concentration of the protein target. Let us assume that the fully bound drug exhibits a¹H chemical shift of while that of the free from resonated at for the same proton (see figure above). If the exchange timescale (i.e. proportional to k_OFF as k_ON is diffusion limited) between the free form of the drug and its bound form is in microseconds, which of the following statements cannot be true assuming that the drug is only 50% bound with its protein target:

A compound with molecule formula C₅H₁₂O₂ has strong infrared absorption at 3300 to 3400 cm^–1. The ¹H NMR spectrum showed three singlet at and ppm; with relative 3:2:1. Addition of D₂O to the sample eliminates the lower field signal. The ¹³C NMR spectrum shows three signals all higher than ppm. Which of the following compounds best fits this data:

The optimized variation wave functions gives: