Polymers Test

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Polymers Test - 24

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Weekly Quiz Competition

Question 1
1 / -0

Which one of the following statements is not true?

A
Buna-S is a copolymer of butadiene and styrene

B
Natural rubber is a 1, 4-polymer of isoprene

C
In vulcanization, the formation of sulphur bridges between different chains make rubber harder and stronger

D
Natural rubber has the trans-configuration at every double bond
Question 2
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The straight chain polymer is formed by :

A
hydrolysis of $$(CH_3)_2SiCl_2$$ followed by condensation polymerization

B
hydrolysis of $$(CH_3)_3SiCl$$ followed by condensation polymerization

C
hydrolysis of $$CH_3SiCl_3$$ followed by condensation polymerization

D
hydrolysis of $$(CH_3)_4Si$$ followed by addition polymerization

Solution

Hint:  The condensation polymerization of $$dimethyl \ dihydroxy \ silane$$ leads to straight-chain polymerization.

Explanation:

A) On hydrolysis, the $$Cl$$ gets replaced by $$OH$$ to form $$dihydroxy \ silane$$ derivative. This can lead to straight-chain polymerization as shown below.

$$(CH_3)_2SiCl_2 \xrightarrow{H_2O} (CH_3)_2Si(OH)_2 \xrightarrow{-H_2O,\ polymerisation} [(CH_3)_2SiO]_n$$

B) On hydrolysis of $$(CH_3)_3SiCl$$,  it forms $$monohydroxy \ silane$$ derivative which leads to branched-chain polymerization.

C) On hydrolysis of $$(CH_3)SiCl_3$$,  it forms $$trihydroxy \ silane$$ derivative which leads to chain termination.

D) $$(CH_3)_4Si$$ is inert to hydrolysis and polymerization due to the lack of $$Cl$$ group.

Therefore, the correct answer is option $$A$$.
Question 3
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Which one of these is a monomer of Bakelite?

A
Vinyl acetate

B
Tetrafluoroethylene

C
Formaldehyde

D
Propylene

Solution

Bakelite is a condensation polymer of phenol and formaldehyde. Bakelite is widely used for making molded products. It was the first plastic made from synthetic components.
Question 4
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The process of addition of sulphur to rubber is called ____________ .

A
vulcenization

B
vulcanization

C
valcanization

D
vulcanisation

Solution

$$\text {Vulcanization}$$ is a chemical process of addition of sulphur.
Hence, the correct option is B.

By this method physical properties of natural rubber are improved. Finished rubber has higher tensile strength and resistance to swelling and abrasion.

Option B is correct.
Question 5
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The monomer that undergo radical polymerisation most easily is:

A
$$CH_{2}=CH_{2}$$

B
$$C_{6}H_{5}CH=CH_{2}$$

C
$$C_6H_6$$

D
$$CH_{3}-CH=CH_{2}$$

Solution

Due to stable benzylic intermediate (stable due to resonance), $$C_6H_5\mathring CH-CH_3$$, it undergoes radical polymerisation most easily. Hence, the correct option is B.
Question 6
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In the process of vulcanization:

A
natural rubber is heated with sulphur

B
natural rubber is heated with carbon

C
natural rubber is heated with phosphorous

D
natural rubber is heated with sodium

Solution

Vulcanization is a chemical process by which the physical properties of natural or synthetic rubber are improved. In its simplest form, vulcanization is brought about by heating rubber with sulfur.
Question 7
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What is the monomer unit for teflon?

A

B

C

D

Solution

Teflon is a plastic-like substance which is produced by polymerizing tetrafluoroethylene ($$CF_{2} = CF_{2}$$).

And is also known as Polytetrafluoroethylene.
Question 8
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The polymer obtained when monomeric unit ($$CH_{2}=C(Cl)-CH=CH_{2}$$) used is:

A
neoprene

B
stilbene

C
styrene

D
chloropicrin

Solution
Question 9
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The non-metal used to treat rubber in the process of vulcanization is:

A
sulphur

B
phosphorus

C
carbon

D
chloride

Solution

The nonmetal used to treat rubber in the process of vulcanization is sulphur. Natural rubber is soft, sticky and has less tensile strength. Vulcanization makes rubber more strong, tough and elastic. Natural rubber is mixed with 3 to 5 % sulphur and heated at 100 to 150 deg C, which results in cross linking of chains of cis-1,4-polyisoprene through disulphide $$\displaystyle (-S-S-)$$ bonds.
Question 10
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Which of the following is a step-growth polymer ?

A
Polyacrylonitrile

B
Polyisoprene

C
Nylon

D
Polythene

Solution

Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long-chain polymers.

For example, Nylon polymerizes by the step-growth polymerization process in which difunctional monomers containing equal parts of amine and carboxylic acid react so that amides are formed at both ends of each monomer
Polyacrylonitrile, Polyisoprene and Polythene polymerize by chain-growth polymerization of acrylonitrile, isoprene ($$2$$-methyl-$$1,\:3$$-butadiene) and ethene, respectively.

Chain-growth polymerization (or addition polymerization) involves the linking together of molecules incorporating double or triple carbon-carbon bonds.