Unit Processes Multiple Choice Questions on “Reactions”.
1. Back mixing can occur only in _________ in a chemical process.
a) Stagnant reaction
b) Flow reaction
c) Both the reactions
d) Does not depend on it
Answer: b
Clarification: Back mixing is the mixing of reactants and products due to flow reaction. It happens in horizontal direction and it reduces the product quality.
2. How many types of reactors are there?
a) 2
b) 3
c) 4
d) Many number
Answer: c
Clarification: There are 4 types of reactors: simple batch homogeneous, semi batch, Continuous homogeneous and continuous heterogeneous reactors.
3. In which reactor one reactant is feed and other reactant is added continuously?
a) Simple batch reactor
b) Semi batch reactor
c) Continuous homogeneous reactor
d) Continuous heterogeneous reactor
Answer: b
Clarification: In Semi batch reactor, it is a type of reactor in which one reactant is already added and another one is continuously added.
4. When a large volume is there, what type of reactor is used?
a) Tubular reactor
b) Simple batch reactor
c) Semi batch reactor
d) Tower reactor
Answer: d
Clarification: Whenever a large volume is there for reaction we use tower reactor. It further consists of empty, packed and baffled tower reactors.
5. Which tower has a horizontal tank, with low ratio of length to diameter?
a) Baffled tank reactor
b) Tower reactor
c) Longitudinal reactor
d) All of the mentioned
Answer: a
Clarification: Only baffled tank has a low length to diameter ratio, and is horizontal in shape.
6. Which reactor has zero back mixing?
a) Tubular reactor
b) Longitudinal reactor
c) Semi batch reactor
d) All of the mentioned
Answer: b
Clarification: Only longitudinal reactor has zero back mixing as the reaction takes place only in one direction and not laterally.
7. What %cent age back mixing takes place in a Stirred tank reactor?
a) 100%
b) 75%
c) 50%
d) 0%
Answer: a
Clarification: Only in a Stirred tank reactor we get 100% back mixing. Hence is has a very low yield.
8. What is the other name of series reaction?
a) Complex reaction
b) Parallel reaction
c) Consecutive reaction
d) None of the mentioned
Answer: c
Clarification: The other name of Series reaction is Consecutive reaction.
9. For a large scale production, which reactor is preferable?
a) Batch reactor
b) Semi batch reactor
c) Continuous reactor
d) None of the mentioned
Answer: c
Clarification: For a large amount of production i.e high yield, a continuous reactor is always preferred.
10. For a high degree of agitation, which reactor is used?
a) Stirred tank
b) Tubular reactor
c) Longitudinal reactor
d) All of the mentioned
Answer: a
Clarification: For high amount of agitation a stirred tank is used because it provides fast reaction. Mechanical agitators are employed in it to provide agitation.