Supercritical Fluid Chromatography - Quiz
  • 1. Which of the following is commonly used as the mobile phase in SFC?
A) Water
B) Acetone
C) Carbon dioxide
D) Methanol
  • 2. What state is the mobile phase in SFC?
A) Solid
B) Gas
C) Liquid
D) Supercritical
  • 3. What is the mechanism of separation in SFC based on?
A) Differences in molecular weight
B) Differences in boiling point
C) Differences in solubility in the mobile phase
D) Differences in conductivity
  • 4. What is the purpose of using a back pressure regulator in SFC?
A) Enhance detector sensitivity
B) Maintain supercritical conditions
C) Increase column temperature
D) Avoid solvent contamination
  • 5. What advantage does SFC offer over traditional HPLC?
A) Limited application range
B) Lower equipment cost
C) Higher resolution
D) Faster separation
  • 6. What role does co-solvent play in SFC separations?
A) Enhances analyte solubility
B) Reduces detector interference
C) Stabilizes column efficiency
D) Improves stationary phase selectivity
  • 7. Which term describes the region where the mobile phase in SFC exhibits properties of both a liquid and a gas?
A) Near-critical region
B) Critical point
C) Transition zone
D) Supercritical zone
  • 8. At supercritical conditions, the density of carbon dioxide is similar to that of which phase?
A) Aqueous
B) Gas
C) Solid
D) Liquid
  • 9. How can the properties of a supercritical fluid be adjusted?
A) Through exposure to light.
B) By changing the pressure and temperature, allowing fine-tuning between liquid-like and gas-like states.
C) By altering its chemical composition.
D) By adding impurities.
  • 10. Under what condition can a binary mixture of supercritical fluids form two immiscible gas phases?
A) In all binary mixtures without exception.
B) At low pressures regardless of temperature.
C) Only when both components have identical critical points.
D) When one component is much more volatile than the other, at high pressure and temperatures above the component critical points.
  • 11. How can the critical point of a binary mixture be estimated?
A) It cannot be estimated; it must always be measured experimentally.
B) As the arithmetic mean of the critical temperatures and pressures of the two components.
C) By summing the critical points of each component.
D) Using only the critical temperature of one component.
  • 12. What methods can provide greater accuracy in calculating the critical point of a binary mixture?
A) Through direct measurement at all possible pressures and temperatures.
B) Equations of state, such as the Peng–Robinson or group-contribution methods.
C) By averaging the boiling points of the components.
D) Using only empirical observations without calculations.
  • 13. What separates the gas and liquid region in a pressure-temperature phase diagram?
A) The density-pressure line
B) The critical point
C) The boiling curve
D) The melting curve
  • 14. What is the surface temperature of Venus in Kelvin?
A) 735 K
B) 300 K
C) 500 K
D) 273 K
  • 15. Why does supercritical water electrolysis improve electrical efficiency?
A) It decreases the need for catalysts.
B) It uses less energy to heat the water.
C) It eliminates bubbles on electrodes, reducing ohmic losses.
D) It increases the volume of hydrogen produced.
  • 16. What is a necessary condition for effective supercritical water hydrolysis?
A) Supercritical conditions can only be achieved at low pressures.
B) Large amounts of water are needed to maintain the reaction.
C) A continuous reaction system must be devised due to very short reaction times.
D) The process requires long reaction times to be effective.
  • 17. What is the surface pressure on Venus in megapascals?
A) 1.0 megapascal
B) 9.3 megapascals
C) 12.0 megapascals
D) 5.0 megapascals
  • 18. Who discovered the critical point of a substance in 1822?
A) Benjamin Thompson
B) Baron Charles Cagniard de la Tour
C) Michael Faraday
D) James Prescott Joule
  • 19. What gases are primarily produced during supercritical water gasification?
A) O2, N2, Ar
B) Neon, Krypton, Xenon
C) NH3, SO2, NOx
D) H2, CH4, CO2, CO
  • 20. What happens to lignin during supercritical water hydrolysis?
A) Lignin is completely converted into simple sugars.
B) Lignin remains unchanged due to short reaction times.
C) Aliphatic inter-ring linkages are cleaved into low molecular weight mixed phenols.
D) Lignin forms a protective layer around polysaccharides.
  • 21. What property does CO2 exhibit at high pressures that is useful for various applications?
A) Reduced density
B) Increased viscosity
C) Enhanced conductivity
D) Antimicrobial properties
  • 22. What is one proposed application of supercritical carbon dioxide in power generation?
A) Brayton cycle
B) Otto cycle
C) The Allam cycle
D) Rankine cycle
  • 23. In which field has supercritical fluid been used to create decaffeinated coffee?
A) Food science
B) Cosmetics
C) Pharmaceuticals
D) Microelectronics
  • 24. What happens to the density of a gas as it approaches the critical temperature?
A) The density fluctuates unpredictably
B) The density decreases significantly
C) The density becomes higher
D) The density remains constant
  • 25. What range of particle sizes can be achieved using supercritical fluids?
A) 10–5000 µm
B) 50–500 nm
C) 5–2000 nm
D) 100–10000 nm
  • 26. What is the critical pressure of carbon dioxide?
A) 3.4 MPa (34 bar)
B) 7.38 MPa (73.8 bar)
C) 570 MPa
D) 40 bar
  • 27. Which natural gas field is known for isolating fossil CO2 and using carbon storage?
A) North Sea gas field
B) Alaska gas field
C) Sleipner gas field
D) Texas gas field
  • 28. Which country has marketed high-temperature domestic water heat pumps using supercritical carbon dioxide?
A) China
B) India
C) South Korea
D) Japan
  • 29. What is the minimum pressure required to compress supercritical CO2 into a solid at certain temperatures?
A) 7.38 MPa (73.8 bar)
B) 14,000 MPa
C) 570 MPa
D) 3.4 MPa (34 bar)
  • 30. What is the main advantage of using supercritical water reactors (SCWRs)?
A) Similar thermal efficiency gains.
B) Increased fuel availability.
C) Reduced radiation exposure.
D) Lower operational costs.
  • 31. What reaction converts vegetable oil into biodiesel?
A) Hydrogenation
B) Oxidation
C) Fermentation
D) Transesterification
  • 32. What is the primary benefit of using supercritical drying in manufacturing aerogels?
A) It speeds up the drying process significantly.
B) It removes solvent without causing distortion due to surface tension.
C) It enhances the mechanical strength of the aerogel.
D) It reduces the cost of materials used.
  • 33. What type of equipment uses liquid CO2 instead of supercritical CO2 to avoid damage?
A) CO2-based dry cleaning equipment.
B) Hydrogen production facilities.
C) Supercritical fluid extraction equipment.
D) Biomass gasification reactors.
  • 34. What is one advantage of using supercritical fluids in chemical reactions?
A) They are cheaper than conventional solvents.
B) They increase reaction time.
C) They eliminate the need for catalysts.
D) Rapid diffusion accelerates diffusion-controlled reactions.
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