This set of Unit Processes Interview Questions and Answers for Experienced people focuses on “Polymer Chemistry Introduction”.
1. Why does polymers do not have a sharp melting point?
a) Identical molecular weight
b) No sharp melting crystals
c) All of the mentioned
d) None of the mentioned
View Answer
Explanation: The reason that polymers do not possess a sharp melting point is twofold. First of all, the polymer is not made up of molecules of identical molecular weight, but contains a mixture of homologues of various degrees of polymerization. Secondly, even if the polymer were of uniform molecular weight, the very size of its large molecules would prevent them from forming the perfect sharp melting crystals which are found in many low molecular weight materials.
2. What are the physical measurements which characterize non polymeric molecules?
a) Freezing-point depressions
b) Vapour pressures
c) Boiling points
d) All of the mentioned
View Answer
Explanation: The various types of physical measurements which can be employed to characterize nonpolymeric molecules, certain ones are of primary importance. Among these are freezing-point depressions, vapour pressures, boiling points, and crystal structure.
3. Fill in the blank: Polymer molecule is _____ than the monomer.
a) Larger
b) Moderate
c) Smaller
d) None of the mentioned
View Answer
Explanation: The reason that methods conventional for low-molecular-weight compounds prove unsatisfactory for polymers arises from the fact that the polymer molecule is so much larger than the monomer.
4. Which state has molecules arranged in complete disorder?
a) Crystalline
b) Amorphous
c) Isentric
d) None of the mentioned
View Answer
Explanation: High-polymeric materials show that the molecules in some of them are arranged in a state of complete disorder (amorphous state); others exhibit a high degree of order (crystalline and oriented states).
5. Which type of materials soften on heating and regains its original shape on cooling?
a) Thermoplastics
b) Thermosetting
c) Rubber
d) All of the mentioned
View Answer
Explanation: Some of them soften upon heating and regain their original hardness upon subsequent cooling, whereby the heating and cooling cycle can be repeated at will. These materials are called thermoplastics.
6. What is the property of thermosetting materials?
a) Regains its original shape
b) Malleable
c) Insoluble and decomposes
d) None of the mentioned
View Answer
Explanation: Others become insoluble and infusible after the first heating and decompose on further increase in temperature. These are called thermosetting materials.
7. How are large molecular complexes built?
a) Association of molecules
b) Secondary bond formation
c) Continuous chemical reaction
d) All of the mentioned
View Answer
Explanation: Large molecular complexes can be built in two possible ways: either by an association of small molecules by meaning of secondary bonds (van der Waals forces, etc.) or by continuous chemical reactions between small molecules, thus establishing strong chemical bonds between them.
8. What is meant by ‘Polyfunctonality’?
a) Formation of polymer
b) Dissociation of polymer
c) Reaction
d) None of the mentioned
View Answer
Explanation: The concept of polyfunctionality of a molecule as a requirement for the formation of polymer.
9. When is a molecule is called bi- or polyfunctional?
a) React at one point
b) Two or more reactive
c) Two reactive points
d) All of the mentioned
View Answer
Explanation: A molecule is called bi- or polyfunctional if two or more reactive or functional groups either are present at the beginning of the reaction or appear in the course of it.
10. The bifunctionality exhibited which type of bond?
a) Double bond
b) Triple bond
c) Both double and triple bond
d) None of the mentioned
View Answer
Explanation: The bifunctionality is exhibited by a large group of molecules containing double or triple bonds.
11. Boron trifluoride, is a highly polar molecule.
a) True
b) False
View Answer
Explanation: By introducing a highly polar molecule such instance, boron trifluoride, BF3, reaction takes place.
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