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