Question 1

Which one of the following is an addition polymer with the same structure as polyethylene except that one hydrogen on every other carbon is replaced by a benzene ring?
Polyvinyl chloride polypropylene polystyrene polyurethane nylon 6,6

Accepted Answer

A)  polystyrene 
B)  polypropylene 
C)  nylon 6, 6 
D)  polyvinyl chloride 
E)  polyurethane

Question 2

In initial steps of the sol- gel process, a reactive metal is treated with an alcohol to form a metal alkoxide. The metal alkoxide is then combined with water to form the metal hydroxide. The metal hydroxide is not formed directly by reaction of the metal with water because .

Accepted Answer

A)  the direct reaction of a reactive metal with water will give a complex mixture of metal oxides and hydroxide 
B)  finer particles are obtained in the two- step process 
C)  the two- step process prevents oxidation of the metal to an unstable oxidation state 
D)  the metal hydroxide formed in the two- step process is more soluble and is more easily utilized 
E)  the alcohol stabilizes the metal hydroxide making it less susceptible to attack by the base added later

Question 3

Natural rubber is too soft and chemically reactive for practical applications. Vulcanization of natural rubber entails _ .

Accepted Answer

A)  crosslinking reactive polymer chains with sulfur atoms 
B)  increasing the average molecular weight of a condensation polymer 
C)  decreasing the average molecular weight of an addition polymer 
D)  conversion of an addition polymer to a condensation polymer 
E)  conversion of a condensation polymer to an addition polymer

Question 4

Silicon technology is based on the fact that silicon oxide is a chemically stable conductor.

Accepted Answer

A) True 
 B)False

Question 5

Vulcanization involves heating rubber with sulfur dioxide to produce a thermosetting polymer.

Accepted Answer

A) True 
 B)False

Question 6

Which type of liquid crystal is colored and changes color with temperature?

Accepted Answer

A)  smectic A 
B)  smectic B 
C)  smectic C 
D)  nematic 
E)  cholesteric

Question 7

As a polymer becomes more crystalline, _.

Accepted Answer

A)  its density decreases 
B)  its stiffness decreases 
C)  its melting point decreases 
D)  its yield stress decreases 
E)  none of the above are correct

Exam 12: Modern Materials

Which one of the following is an addition polymer with the same structure as polyethylene except that one hydrogen on every other carbon is replaced by a benzene ring? Polyvinyl chloride polypropylene polystyrene polyurethane nylon 6,6