Lesson 19C.2
19C.2 HPLC and GC Quiz: Pearson Edexcel Chemistry, Unit 19
20 questions
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Lesson 19C.2, HPLC and GC: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 19: Modern Analytical Techniques II, written with Revision Ninja.
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The 20 questions
-
What determines the retention time of a substance in high performance liquid chromatography?
- Detector temperature only
- Column length only
- Relative phase interactions
- Sample mass only
-
Which type of mixture is best suited for analysis by gas chromatography?
- Insoluble polymers
- Thermally unstable solids
- Volatile, stable compounds
- Non-volatile ionic compounds
-
Why is mass spectrometry coupled as a detector in gas chromatography?
- To increase yield
- To speed up elution
- To identify compounds
- To separate mixtures
-
What is a major advantage of high-performance liquid chromatography over paper chromatography?
- Higher sensitivity
- Slower separation
- Qualitative analysis only
- Destroys the sample
-
In sports drug testing, what is the main function of mass spectrometry after gas chromatography?
- Separating mixtures
- Identifying components
- Increasing volatility
- Dissolving samples
-
What can be concluded if an unknown compound matches a standard's retention time in GC?
- Compound is pure
- Identity is confirmed
- Compound is unreactive
- Identity is possible
-
Why is an inert carrier gas used as the mobile phase in gas chromatography?
- Prevents chemical reactions
- Increases sample boiling
- Reacts with packing
- Reduces retention times
-
What acts as the mobile phase in high-performance liquid chromatography?
- Solid silica gel
- High-pressure liquid solvent
- Inert carrier gas
- Gaseous helium
-
Which type of substance is most suitably analysed using HPLC rather than GC?
- Inert noble gases
- Non-volatile compounds
- Low-boiling alkanes
- Volatile hydrocarbons
-
Why is the column in HPLC packed with very fine particles?
- Speeds up elution
- Decreases surface area
- Increases surface area
- Lowers column pressure
-
A GC-MS peak has a molecular ion peak at m/z = 46. Which compound is present?
- Ethanal
- Ethanol
- Propan-1-ol
- Methanol
-
Which mixture is best analysed using gas chromatography rather than HPLC?
- High-melting ionic salts
- Thermally unstable proteins
- Volatile hydrocarbons
- Non-volatile polymers
-
What parameter is compared against reference standards to identify compounds in gas chromatography?
- Peak height
- Melting point
- Retention time
- Peak width
-
An unknown compound has M+ at m/z 74 and a strong peak at m/z 31. Which compound fits?
- Ethanoic acid, CH3COOH
- Propanone, CH3COCH3
- Benzene, C6H6
- Butan-1-ol, C4H9OH
-
Two GC peaks show retention times of 3.2 min and 9.6 min. Which is more volatile?
- 3.2 min peak
- Neither peak
- Both equal
- 9.6 min peak
-
Why is HPLC preferred over GC for analysing thermally unstable pharmaceuticals?
- Lower operating temperatures
- Vaporises the sample
- Uses flame ionisation
- High operating temperatures
-
Why is mass spectrometry combined with gas chromatography in mixture analysis?
- MS separates mixtures
- GC separates mixtures
- MS increases pressure
- GC identifies masses
-
What does a larger peak area on a gas chromatogram represent?
- Higher boiling point
- Greater relative amount
- Greater molar mass
- Slower flow rate
-
Which detector is commonly used in HPLC for compounds containing chromophores?
- UV-visible detector
- Flame ionisation detector
- Mass spectrometer
- Thermal conductivity detector
-
Which unit is typically used to report retention time in gas chromatography?
- Hours
- Milliseconds
- Seconds
- Minutes
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