161. Composition of Ziegler-Natta catalyst is
A
$${\left( {E{t_3}} \right)_3}Al \cdot TiC{l_2}$$
B
$${\left( {Me} \right)_3}Al \cdot TiC{l_2}$$
C
$${\left( {Et} \right)_3}Al \cdot TiC{l_4}$$
D
$${\left( {Et} \right)_3}Al \cdot PtC{l_4}$$
Answer :
$${\left( {Et} \right)_3}Al \cdot TiC{l_4}$$
162. High density polythene is obtained by
A
polymerisation of ethene in a hydrocarbon solvent in the presence of Ziegler-Natta catalyst
B
polymerisation of ethene under high pressure and temperature
C
free radical polymerisation of ethene at low temperature in presence of peroxide
D
polymerisation of ethene in presence of carbon tetrachloride
Answer :
polymerisation of ethene in a hydrocarbon solvent in the presence of Ziegler-Natta catalyst
163. Bakelite is an example of
A
elastomer
B
fibre
C
thermoplastic
D
thermosetting
Answer :
thermosetting
164. The formation of which of the following polymers involves hydrolysis reaction?
A
Nylon 6
B
Bakelite
C
Nylon 6, 6
D
Terylene
Answer :
Nylon 6
because 2-methylpropene shows cationic polymerisation. 166. Glyptals are chiefly employed in
A
toy making
B
surface coating
C
photofilm making
D
electrical insulators
Answer :
surface coating
167. Thermosets are :
A
cross-linked polymers
B
don’t melt or soften on heating
C
cross-linking is usually developed at the time of moulding where they harden reversibly
D
all of the above
Answer :
all of the above