This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Chemistry of Polymerization Reaction”.
1. A polymerization reaction can be what?
a) Condensation reaction
b) Hydrogenation reaction
c) Substitution reaction
d) Rearrangement reaction
View Answer
Explanation: Polymerization reactions are either condensation reactions or addition reactions.
2. Which reaction of polymerization proceeds step-wise?
a) Addition reaction
b) Condensation reaction
c) Substitution reaction
d) None of the mentioned
View Answer
Explanation: The polymer formation in condensation polymerization proceeds stepwise, the various intermediates, dimer, trimer, etc., existing as stable molecules until the next reaction step. Small molecules, usually water, are split off at each step of the reaction.
3. Polymerization at the double bond is a typical addition reaction.
a) True
b) False
View Answer
Explanation: During the addition reaction, no stable compounds are formed because the intermediates are comparatively short-lived radicals or ions. The formation of the polymer chain is usually accomplished in a fraction of a second and in one single sweep. Polymerization at the double bond is a typical addition reaction of this type.
4. Polycondensation proceed in which type of molecular weight reaction?
a) High
b) Moderate
c) Low
d) None of the mentioned
View Answer
Explanation: Polycondensation proceeds fundamentally in the same manner as condensations between low-molecular-weight substances.
5. Addition polymerization differ on what basis?
a) Kinetic energy
b) Reaction mechanism
c) Behavior
d) All of the mentioned
View Answer
Explanation: Two types of addition polymerization exist that differ in their reaction mechanism and their kinetic behavior from each other and from polycondensations.
6. Whether or not an active center can be formed.
a) Yes
b) No
View Answer
Explanation: Whether or not an active center can be formed, i.e., whether or not an unsaturated molecule is suitable for addition polymerizations depends on a number of factors. In the first place, the energy necessary to open one of the two links of an aliphatic double bond depends upon the nature of the two atoms that are linked together by it, for instance, C=C or C=O. The electronic configurations of each of these atoms and the distances between them influence the dissociation energy of the double or triple bond.
7. The energy required to activate the bond is influenced by what?
a) Substituents on the atoms
b) Temperature
c) Pressure
d) All of the mentioned
View Answer
Explanation: The energy required to activate the bond is influenced by two more factors: (1) the substituents on the atoms which form the multiple bond and (2) the presence of conjugated or cumulated multiple bonds.
8. The tendency to decrease polymerization can be achieved by what?
a) Steric hindrance
b) Resonance stability
c) Steric hindrance & Resonance stability
d) None of the mentioned
View Answer
Explanation: The tendency to polymerize decreases rapidly, presumably because of steric hindrance or resonance stabilization.
9. The ease of polymerization increases with the amount of unsaturation.
a) True
b) False
View Answer
Explanation: The ease of polymerization increases with the amount of unsaturation and that conjugation or accumulation of double bonds increases their reactivity.
10. Which of the following is an active center in initiating systems?
a) Free radicals
b) Carbonium ions
c) Carbanions
d) All of the mentioned
View Answer
Explanation: Initiators, or initiating systems, generate three distinct types of active centers and unstable intermediates: (1), free radicals, (2), carbonium ions, (3), carbanions.
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