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# Separation Processes MCQ’s – Algebraic Method for Determining N

1 - Question

What does N stand for?

a) Number of processes

b) Number of stages

c) Number of equipment

d) Ratio of feed to product

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Answer: bExplanation: N stands for the number of stages corresponding to a cascade.

2 - Question

When does the graphical method become tedious?

a) When there are too many solvents

b) When too many stages are involved

c) When more than one solute is adsorbed or stripped

d) When the solute to be stripped is unknown

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Answer: cExplanation: The graphical method becomes tedious when more than one solute is adsorbed or stripped.

3 - Question

Which method is applied when graphical method is unsuitable?

a) Keller method

b) Newton’s method

c) Distillation method

d) Kremser method

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Answer: dExplanation: Kremser method is applied when graphical method is unsuitable.

4 - Question

What is the formula for fraction of the solute i absorbed?

a) A i N+1 – 1/ A i N+1 –A i

b) A i N+1 – A i / A i N+1 –1

c) S i N+1 – S i / S i N+1 –1

d) S i N+1 – A i / S i N+1 –1

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Answer: bExplanation: The formula for fraction of the solute I absorbed is A i N+1 – A i / A i N+1 –1 where A i = L/K i V.

5 - Question

What is the formula for fraction of the solute i stripped?

a) A i N+1 – 1/ A i N+1 –A i

b) A i N+1 – A i / A i N+1 –1

c) S i N+1 – S i / S i N+1 –1

d) S i N+1 – A i / S i N+1 –1

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Answer: cExplanation: The formula for fraction of the solute I stripped is S i N+1 – S i / S i N+1 –1 Where S i = K i V/L

6 - Question

Which of the following does not give a correct expression for K i ?

a) Roult’s law

b) Henry’s law

c) Modified Roult’s law

d) Gas law

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Answer: dExplanation: The gas law is PV=nRT and it does not give an expression for K i .

7 - Question

When is the Roult’s law used?

a) Ideal solutions involving solutes at sub-critical temperatures

b) Non-ideal solutions involving solvents at sub-critical temperatures

c) Ideal solution involving solutes at critical temperatures

d) Non-ideal solutions involving solutes at critical temperatures

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Answer: aExplanation: The roullt’s law where K i = P s i /P is applied for Ideal solutions involving solutes at sub-critical temperatures

8 - Question

Which equation is used for solutes at supercritical temperatures?

a) Roult’s law

b) Henry’s law

c) Modified Roult’s law

d) Gas law

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Answer: bExplanation: The henry’s law which is K i =H i /P is used for solutes at supercritical temperatures.

9 - Question

Which equation is sued for sparingly soluble solutes at sub-critical temperatures?

a) Roult’s law

b) Henry’s law

c) Modified Roult’s law

d) Solubility equation

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Answer: dExplanation: The solubility equation K i = P s i /x * i P is used for sparingly soluble solutes at sub-critical temperatures.

10 - Question

What is the formula for solute absorption factor?

a) Ai = LV/Ki

b) Si = Ki V/L

c) Ai =L/Ki V

d) Si = Ki /LV

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Answer: cExplanation: Ai =L/Ki V is the formula for solute absorption factor where L and V are the feed rates.