Topic 19 - Exam-style

Chromatography is used to separate the components of a mixture and can be carried out in a range of different ways. A suitable example of a ‘carrier gas’ in gas chromatography is: A) Chlorine B) Nitrogen C) Steam D) Not possible to state, as there should be a vacuum

Chromatography is used to separate the components of a mixture and can be carried out in a range of different ways. Separation is achieved in gas chromatography due to the components in the mixture having different: A) interactions with the stationary phase B) interactions with the mobile phase C) colours D) solubility in the moving solvent

Which gas is the least suitable as a carrier gas in Gas-Liquid Chromatography?: A) Agron B) Carbon dioxide C) Oxygen D) Nitrogen

Chromatography may be used to separate mixtures of amino acids. This is best explained by the fact that different amino acids have different interactions with: A) the mobile phase only B) the stationary phase only C) the mobile phase and the stationary phase D) ninhydrin

Ninhydrin is used in thin-layer chromatography to help with the identification of amino acids. This is because the ninhydrin: A) reacts with amino acids to form a compound which has an intense colour. B) reacts with amino acids to form compounds each of which has a characteristic colour. C) increases the separation of the amino acids on the chromatogram. D) ensures that the mobile phase maintains a nearly constant pH for all the amino acids.

In one type of high-performance liquid chromatography (HPLC), the stationary phase is non-polar and a polar solvent is used as the eluent. Which of the following would travel through the chromatography column most quickly? A) Tetrachloromethane B) Chloromethane C) Iodomethane D) Hexane

In gas chromatography, mixtures are passed through a long tube containing a liquid as the stationary phase. The mixtures are separated into their components because the components differ in: A) relative molecular mass. B) melting temperature. C) volatility. D) force of attraction to the liquid.

The distance on a chromatogram moved by an individual amino acid, in a mixture of different amino acids, mainly depends on: A) the molar mass of the amino acid. B) the molar mass of the solvent used. C) the intermolecular forces between the solvent and the stationary phase. D) the intermolecular forces between the amino acid and both the solvent and the stationary phase.

The spectra of the compounds with the formulae CH3CH(OH)CH3 and CH3CH2CH2OH can be distinguished by: A) the value of m/e of the molecular ion in the mass spectrum. B) the presence of a fragment with m/e =15 in the mass spectrum. C) the presence of an absorption peak due to O–H in the infrared spectrum. D) the number of peaks in the nmr spectrum.

Which of the following has two singlet peaks in its nmr spectrum?: A) Methanal, HCHO B) Methanol, CH3OH C) Chloromethane, CH3Cl D) Dichloromethane, CH2Cl2

How many different peaks due to hydrogen atoms would you expect to see in a low resolution proton nmr spectrum of propanoic acid, CH3CH2COOH? A) Two B) Three C) Five D) Six

In a high resolution proton nmr spectrum of ethanoic acid, CH3COOH, the peak due to the hydrogen atoms in the methyl group would be a A) singlet B) doublet C) triplet D) quartet

Which atoms are not detected by X-rays but are detected by nuclear magnetic resonance imaging which also shows their environments?: A) Carbon B) Hydrogen C) Nitrogen D) Oxygen