11. The species which can best serve as an initiator for the cationic polymerization is :
A
$$LiAl{H_4}$$
B
$$HN{O_3}$$
C
$$AlC{l_3}$$
D
$$BaLi$$
Answer :
$$AlC{l_3}$$
12. Which of the following is not true for thermoplastic polymers?
A
Thermoplastics are linear polymers.
B
They soften and melt on heating.
C
Molten polymer can be remoulded into any shape.
D
They have cross-linkages which break on heating.
Answer :
They have cross-linkages which break on heating.
13. Which of the following represents chloroprene, the monomer of neoprene?
A
$$C{H_2} = CH - CH = C{H_2}Cl$$
B
\[C{{H}_{2}}\underset{\begin{smallmatrix}
| \\
\,\,\,C{{H}_{3}}
\end{smallmatrix}}{\mathop{=C-}}\,CH=CHCl\]
C
\[C{{H}_{2}}\underset{\begin{smallmatrix}
| \\
Cl
\end{smallmatrix}}{\mathop{=C-}}\,CH=C{{H}_{2}}\]
D
\[C{{H}_{2}}\underset{\begin{smallmatrix}
| \\
\,\,\,C{{H}_{3}}
\end{smallmatrix}}{\mathop{=C-}}\,\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\, \\
Cl\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{C=}}\,C{{H}_{2}}\]
Answer :
\[C{{H}_{2}}\underset{\begin{smallmatrix}
| \\
Cl
\end{smallmatrix}}{\mathop{=C-}}\,CH=C{{H}_{2}}\]
14. Which one of the following statements is wrong?
A
$$PVC$$ stands for poly vinyl chloride.
B
$$PTFE$$ stands for teflon.
C
$$PMMA$$ stands for polymethyl methyl acrylate.
D
Buna-$$S$$ stands for natural rubber.
Answer :
Buna-$$S$$ stands for natural rubber.
15. Which of the following is a condensation polymerisation?
A
Teflon
B
$$PVC$$
C
Polyester
D
Neoprene
Answer :
Polyester
16. Which one of the following is an example of a thermosetting polymer?
A
B
C
D
Answer :
and $$PVC$$
are thermoplastic polymers
17. Which one of the following statements is not true?
A
In vulcanisation, the formation of sulphur bridges between different chains make rubber harder and stronger
B
Natural rubber has the $$trans$$ - configuration at every double bond
C
Buna - $$S$$ is a copolymer of butadiene and styrene
D
Natural rubber is a 1, 4 - polymer of isoprene
Answer :
Natural rubber has the $$trans$$ - configuration at every double bond
18. Which of the following is not a semi-synthetic polymer?
A
$$cis$$ - Polyisoprene
B
Cellulose nitrate
C
Cellulose acetate
D
Vulcanised rubber
Answer :
$$cis$$ - Polyisoprene
19. Which of the following alkenes is least reactive towards anionic polymerisation?
A
$$C{H_2} = CHC{H_3}$$
B
$$C{H_2} = C{F_2}$$
C
$$C{H_2} = CHCN$$
D
$$C{H_2} = CH{C_6}{H_5}$$
Answer :
$$C{H_2} = CHC{H_3}$$
20. Novolac on heating with formaldehyde undergoes ________ to form an infusible solid mass called ________.
A
polymerisation, melamine
B
vulcanisation, resin
C
cross-linking, bakelite
D
condensation, polystyrene
Answer :
cross-linking, bakelite