Physical Chemistry Answers

Calculate the volume of NH3 gas at STP when 84 g of N2 is reacted with H2

Which of the following(s) is(are) the disadvantage of mass spectrometry?

      I.    It can not be hyphenated with HPLC or GC

     II.    Not useful in structural characterization

   III.    High maintenance of instruments

   IV.    Not useful in quantification

    V.   Trained personnel for the operation

a. II, IV, V

b. III and V

c.IV and V

d. III, IV, V

e. I, II and III

f. II, III and V

g. II and III

Mass spectrometry is combined with chromatography to separate the molecules in complex mixtures and then structurally characterize them by NMR.

Why hyphenated techniques of NMR with liquid chromatography is not widespread?

a.D-labelled solvents used are expensive

b. NMR is a not a continuous injection technique

c. Magnetic field used in NMR causes fluctuations in NMR

d. Interfaces between NMR and chromatography destroys samples

e. Pumping system of HPLC damages NMR

f. The ion source requires conversion of the sample to the gas phase

Which one of the following species is a derivatization reagent according to the paragraph about the determination of a residual glutaraldehyde in a polymeric film?

   I.   Pentafluorobenzyl oxime

  II.   Hydrazine

 III.   Formaldehyde

 IV.   Dinitrophenylhydrazine

 V.   Benzaldehyde

a. I, IV, V

b. I, II, III, V

c. I, II, III, IV

d. I, III, IV

e. I, II, IV

What can be said about the selectivity of the UV-Vis spectroscopy?

a. UV-Vis has high selectivity

b. UV-Vis is selective towards saturated hydrocarbons

c. Compounds in complex mixtures are separated well

d. UV Vis spectroscopy is highly selective for the benzene

e. Selectivity for the compounds absorbing at visible wavelengths is high

Which of the following ionization technique is suitable for the ionization of the non-volatile non-polar compounds?

      I.    ESI

     II.    EI

   III.    APCI

a. Only III

b. Only I

c. Only II

d. II and III

e. I and III

In quantitation of penicillin by UV Vis spectroscopy, which one of the following is correct?

      I.    Imidazole is a derivatization reagent

     II.    Penicillin does not have a chromophore

   III.    Penicillin derivatize has a maximum absorbance somewhere between 325 and 345 nm

a. I and III

b. II and III

c. Only II

d. I and II

e. I, II and III

How does CID is achieved?

a. By reacting ions formed in ESI with reagent and proton transfers

b. By applying stages of vacuum prior to entering MS analyzers

c. By applying heat to the multiply charged ions

d.By colliding accelerated ions formed in ESI with neutral gas in mass analzyers

e. By applying voltage to the charged needle

f. By applying heat under stream of nitrogen

Which regions of infrared spectroscopy is suitable for quality control of pharmaceuticals?

a. 0.5 - 0.025 eV

b. 50 - 1000 um

c. 200 - 10 cm^_1

d. 2.5 - 50 um

e. 0.8 - 2.5 mm

What do we obtain upon CID?

     I.    Fragmentation of the precursor ions

     II.    Fragmentation of the parent ion

   III.    Fragmentation of product ions

a. II and III

b. I and III

c. I and II

d. Only I

e. I, II and III