Food Engineering Multiple Choice Questions on “Unit Operations – Extraction-1”.
1. Liquid-liquid extraction is called leaching.
a) True
b) False
Answer: b
Clarification: Solid-liquid extraction is called leaching.
2. If extraction is done at the _____ of the solvent, it is called _____
a) Melting point, decoction
b) Boiling point, decoction
c) Melting point, leaching
d) Boiling point, leaching
Answer: b
Clarification: If extraction is done at the boiling point of the solvent, it is called decoction.
3. Statement 1: Soya bean has a high oil content.
Statement 2: If the oil content is high, extraction is done by solvent extraction alone.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: c
Clarification: Soya bean has low oil content. If the oil content is low, extraction is done by solvent extraction alone.
4. Oil seed cakes are obtained by _____
a) Solvent extraction
b) Mechanical pressing
c) None of the mentioned
d) Solvent extraction & Mechanical pressing
Answer: b
Clarification: Oil seed cakes are obtained by mechanical pressing.
5. Statement 1: Partition coefficient pertains to solid-liquid extraction.
Statement 2: Leaching involves both heat and mass transfer.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: c
Clarification: Partition coefficient pertains to liquid-liquid extraction. Leaching involves mass transfer.
6. Which among the following factors does NOT affect extraction?
a) Solubility of solute in the solvent
b) Degree of agitation
c) Concentration difference
d) None of the mentioned
Answer: d
Clarification: All the given factors affect extraction.
7. Multi-stage counter-current extraction is expensive as more extractors are needed to strip the solid off the solvent.
a) True
b) False
Answer: a
Clarification: Multi-stage counter-current extraction is expensive as more extractors are needed to strip the solid off the solvent.
8. Statement 1: Multi-stage cross-current extraction – the solids contain some amount of solute after every extraction.
Statement 2: Single-stage batch extractor – Used in labs and not on large scale as a solvent is continuously subjected to heat.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: c
Clarification: Single-stage batch extractor – the solids contain some amount of solute after every extraction. Multi-stage cross-current extraction – Used in labs and not on large scale as a solvent is continuously subjected to heat.
9. _____ is the diagonal of the x-y diagram.
a) Operating line
b) Equilibrium line
c) Equilibrium curve
d) None of the mentioned
Answer: b
Clarification: Equilibrium line is the diagonal of the x-y diagram.
10. Statement 1: In counter-current extraction, equilibrium is reached at every stage.
Statement 2: Right angled triangle method also called a difference point method is used to calculate the ideal number of stages for extraction.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: b
Clarification: Both statements are true. In counter-current extraction, equilibrium is reached at every stage. Right angled triangle method also called a difference point method is used to calculate the ideal number of stages for extraction.