141. Phosphates (e.g., tricresyl, tributyl, tetrabutyl, triphenyl etc.) are added to polymers to act as
Hardeners
Anti-shrinkage agents
Plasticisers
Transparency improver
Correct answer: (C) Plasticisers
142. Phthalic anhydride is used
In making PVC
As plasticisers
In insecticides manufacture
For making nylon-6
Correct answer: (B) As plasticisers
143. Pick out the correct statement.
Plastics are good conductors of heat and electricity
All the polymers are highly crystalline in nature
Polymers can be vaporised by heating to a very high temperature
The liquid polymer becomes greasy, then waxy and finally solid on increasing the degree of polymerisation
Correct answer: (D) The liquid polymer becomes greasy, then waxy and finally solid on increasing the degree of polymerisation
144. Pick out the wrong statement regarding the solubility characteristics of high polymers.
Greater the degree of cross-linking in the polymer, lesser is its solubility
Polymers having more aliphatic character are more soluble in aliphatic solvents, while those polymers having more aromatic character are more soluble in aromatic solvents
Swelling tendency or solubility of polymers in a particular solvent decreases with increase in molecular weight of the solvent
High molecular weight polymers on dissolving gives solution of very low viscosity
Correct answer: (D) High molecular weight polymers on dissolving gives solution of very low viscosity
145. Pick out the wrong statement.
For the manufacture of styrene, the major raw materials are benzene and ethylene
One important copolymer of styrene is SBR, which is widely used in the manufacture of automobile tyres
Manufacture of phenol by chloroben-zene-eaustic process involves. The chlorination of benzene, causticisation and hydrolysis
Phenol manufacture by chlorobenzene-caustic process is competitive even when low cost chlorine is not available
Correct answer: (D) Phenol manufacture by chlorobenzene-caustic process is competitive even when low cost chlorine is not available
146. Plastic articles are normally produced by _________ moulding.
Green sand
Injection
Shell
Dry sand
Correct answer: (B) Injection
147. Plastic tubes & pipes are generally made by _________ moulding.
Injection
Transfer
Extrusion
Compression
Correct answer: (C) Extrusion
148. Plasticisers are added to synthetic plastics to
Impart flexibility
Improve workability during fabrication
Develop new improved properties not present in the original resin
All (A), (B) and (C)
Correct answer: (D) All (A), (B) and (C)
149. Plasticisers are high boiling liquids added to plastic polymers to impart toughness and flexibility at ordinary temperature. Which of the following is not a plasticiser?
Ethylene glycol
Stearic acid estors
Tricresyl phosphate
Esters of phthalic acid
Correct answer: (A) Ethylene glycol
150. Plexiglass (also called Lucite) because of its high optical transparency is used for making lenses. It is chemically