Engineering Questions with Answers - Multiple Choice Questions

Polymer Engineering MCQ’s – Radical Chain Polymerization

1 - Question

Which of the following can activate chain initiation?
a) heat
b) light or radiation
c) catalysts
d) all of the mentioned
View Answer Answer: d
Explanation: The chain initiation can be induced by heat, light or energy radiations or with the help of initiators or catalysts.



2 - Question

Which of the following monomers cannot undergo chain growth polymerization?
a) CH2═ CH2
b) CH2═CHCN
c) CH2═CHCOOR
d) COOH−CH2−COOH
View Answer Answer: d
Explanation: Dicarboxylic acid undergoes condensation polymerization.



3 - Question

Why is addition polymerization also known as vinyl polymerization?
a) monomers are unsaturated compounds
b) its a chain reaction
c) most monomers contain (CH2═CH─) group
d) all of the mentioned
View Answer Answer: c
Explanation: Most of the monomers involves in chain polymerization contains (CH2═CH─) group, which is commonly known as vinyl group.



4 - Question

Which of the following cannot initiate the chain reaction in polymerization of acrylo-nitrile?
a) anion
b) cation
c) free radical
d) coordination
View Answer Answer: b
Explanation: Acrylonitrile contains ─CN group which is an electron withdrawing group and cannot adopt a cationic pathway. Anion, free radical and coordination complex can polymerize it to high molecular weight polymer.



5 - Question

What does chain initiation step of free radical polymerization consists of?
a) decomposition of initiator
b) addition of free radical to monomer
c) all of the mentioned
d) none of the mentioned
View Answer Answer: c
Explanation: The first step in chain initiation is decomposition of initiator to free radicals and the second step is addition of free radical to the monomer unit.



6 - Question

Which is the rate determining step of chain initiation step?
a) initiator decomposition
b) chain initiation of monomer
c) chain propagation
d) none of the mentioned
View Answer Answer: a
Explanation: Initiator decomposition step is the rate determining step of chain initiation step as it is the slowest of two.



7 - Question

Which mode in the chain termination step is accompanied by a transfer of hydrogen molecule?
a) combination
b) disproportionation
c) propagation
d) all of the mentioned
View Answer Answer: b
Explanation: The disproportionation mode of termination is accomplished by a hydrogen transfer from one radical molecule to other, which is given by- R~~~ CH2−∙CHX + XH∙C−CH2 ~~~~~R → R ~~~ CH2− CH2X + R~~~ CH═CHX.



8 - Question

The substance that is so effective, which can suppress the rate as well as degree of polymerization is a ___________
a) retarder
b) inhibitor
c) promoter
d) none of the mentioned
View Answer Answer: b
Explanation: If an inhibitor is added to a monomer, then it may reduce the rate of reaction and may even suppress degree of polymerization.



9 - Question

Which of the following mechanism can occur for the termination step to take place?
a) combination
b) disproportionation
c) all of the mentioned
d) none of the mentioned
View Answer Answer: c
Explanation: Combination and disproportionation both are the modes of termination step of free radical polymerization.



10 - Question

Which of the following factors does termination mechanism depend on?
a) type of active centre
b) nature of monomer
c) reaction conditions
d) all of the mentioned
View Answer Answer: d
Explanation: The convenient mechanism for chain termination largely depends on all the above factors.

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