1. Why is it important to seal the jar containing the TLC plate?
- to allow the process to occur
- to prevent bacteria contaminating the sample
- to slow the evaporation of the solvent from the TLC plate
- to speed up evaporation of the solvent
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2. What is the definition of retention time?
- the time taken for a particular compound to travel through the column to the detector, from injection to leaving the column
- the time taken for a particular compound to dissolve in the stationary phase
- the time taken for the gas to be injected into the column and dissolve in the stationary phase
- distance moved by component divided by distance moved my solvent front
3. What is the benefit of coupling gas chromatography with mass spectrometry
- gas chromatography separates compounds and mass spectra can be compared to a database
- both the retention time and mass spectra can be used to improve the reliability of the identification
- mass spectroscopy separates the compounds and retention times can be compared to a database
4. Which is NOT a use of GC-MS?
- drug testing
- airport security
- treatment of strokes
- forensic analysis
5. Which is NOT a limitation of thin layer chromatography?
- unknown compounds have no Rf value for comparison
- may be difficult to find a solvent which will separate all components
- similar compounds have similar retention times
- similar compounds have similar Rf values