Multiple choice question for engineering
Set 1
1. Consider a reaction of polymer formation by condensation polymerization, completed in n-steps, with the liberation of a certain byproduct. How many total molecules of byproduct are released as a result of complete reaction?
a) n+1
b) n
c) n-1
d) n/2
Answer
Answer: b [Reason:] At each step of a condensation polymerization reaction, one byproduct molecule is released. So a total of n molecules are liberated.
2. How many molecules of hydrochloric acid are released when n monomers of di-acid chloride and n monomers of di-alcohol are reacted to form a polymer?
a) 2n
b) n-1
c) 2n-1
d) n
Answer
Answer: c [Reason:] Here, the reaction between the monomers completes in (2n-1) number of steps. So, the molecules released will also be 2n-1.
3. Which of the byproduct molecule is released in the formation of polyurea?
a) NH3
b) H2O
c) HCl
d) no elimination
Answer
Answer: d [Reason:] There is no byproduct elimination in this reaction.
Formation of urea-
─N═C═O + H2N─ ↔ ─NHCO─NH─
Formation of polyurea-
nOCRNCO + n H2NR’NH2 ↔ OCN─[─RNHCO─HNR’NHCONH]n-1─RNHCONHR’NH2.
4. Which of the following byproduct is released when an amine reacts with acid chloride?
a) HCl
b) H2O
c) NH3
d) no elimination
Answer
Answer: a [Reason:] The amidation reaction is given by-
─NH2 + ─COCl ↔ ─NH─CO─ + HCl.
5. Which of the following byproduct is released when an ester reacts with alcohol?
a) alcohol
b) water
c) ether
d) no elimination
Answer
Answer: a [Reason:] The reaction is given by-
─COOR1 + R2OH ↔ ─COOR2 + R1OH
Thus, the byproduct is alcohol.
6. Which of the following reactants react to give amidation reaction?
a) amine and acid
b) amine and alcohol
c) amine and ester
d) ester and alcohol
Answer
Answer: a [Reason:] The reaction of amine with acid is an amidation reaction which is given by-
─NH2 + ─COOH ↔ ─NH─CO─ + H2O.
7. Which of the following does not result in the formation of an ester?
a) acid and alcohol
b) acid chloride and alcohol
c) ester and alcohol
d) amine and acid
Answer
Answer: d [Reason:] The reaction of acid and acid chloride with alcohol is an esterification reaction, and even the reaction of ester and alcohol give rise to formation of ester. Amine and acid react to give amide group.
8. Consider the following statements for condensation polymerization-
I. Bifunctional or polyfunctional monomers
II. Loss of each kind of functional group in each step for bifunctional species
III. Always accompanied by the release of a byproduct molecule
IV. Monofunctional or polyfunctional monomers
Which of the following are true?
a) I and II
b) I, II and III
c) I and III
d) III and IV
Answer
Answer: a [Reason:] III is not true because in some reactions, there is no elimination of any molecule. Besides, monofuntional monomers fail to complete the reaction. At each step of reaction, two functional groups, one of each kind, are lost.
9. What is the product of following polymerization reaction?
↔
a) [─R─CO─]
b) [─O─R─CO─]n
c) [O─CR─O─]n
d) [─O─R─CO─]n-1
Answer
Answer: b [Reason:] The lactone ring opens by breaking C─O bond and polymerizes to give [─O─R─CO─]n.
10. What is the product of following polymerization reaction?
↔
a) ─[─NH─R─CO─]n
b) ─[─R─NH─CO─]n
c) ─[─NH─R─CO─]n-1
d) none of the mentioned
Answer
Answer: a [Reason:] The lactam group polymerizes to give ─[─NH─R─CO─]n product, consisting of amide group.
Set 2
1. Which of the following polymer type is not classified on the basis of its application and properties?
a) rubbers
b) plastics
c) fibres
d) synthetic
Answer
Answer: d [Reason:] Synthetic polymers are classified on the basis of their origin and are known as man-made polymers.
2. Which of the following is a thermosetting polymer?
a) polystyrene
b) polyolefins
c) nylons
d) phenolic resins
Answer
Answer: d [Reason:] Phenolic resins falls under the clan of thermosetting polymers and rest are thermoplastic polymers which can be softened repeatedly on the application of heat.
3. The characteristics of condensation polymerization are given below-
I. only −C−C− linkages present in the polymer structure
II. use of bifunctional or polyfunctional monomers
III. elimination of a small byproduct molecule
Which of the following is true?
a) I, II, III
b) II and III
c) I and II
d) Only III
Answer
Answer: b [Reason:] Besides −C−C− linkages, polymer structure also contains atoms as O, N, etc., at regular intervals in the main chain.
4. Which of the following monomers are unsuitable for condensation polymerization?
a) propanoic acid and ethanol
b) butane-dioic acid and glycol
c) diamines and dicarboxylic acids
d) hydroxy acids
Answer
Answer: a [Reason:] Propanoic acid and ethanol, both are monofunctional monomers which are not suitable for a polycondensation reaction to take place.
5. Which of the following is true for the resultant polymer product formed, when molecules of pthalic acid react with molecules of glycerol?
a) branch polymer
b) cross-link polymer
c) linear polymer
d) none of the mentioned
Answer
Answer: b [Reason:] The reaction between pthalic acid and glycerol initially results into linear or branched polymer but, due to trifunctionality of glycerol, ultimately cross-linking takes place between the molecules.
6. Which among the following polymers have lowest solubillty?
a) polyethylene
b) polystyrene
c) nylon 6
d) epoxy resin
Answer
Answer: d [Reason:] Epoxy resin is a cross-linking polymer which has lowest solubility among them.
7. Which of the following polymer exhibit a lower value of molar cohesion?
a) wool
b) silk
c) vulcanized rubber
d) polystyrene
Answer
Answer: c [Reason:] Rubbers have the lowest value of molar cohesion in comparison to plastics and fibres.
8. What is the range of tensile strength, exhibited by fibres?
a) 300-3,000
b) 4,000-15,000
c) 20,000-150,000
d) 5,000-10,000
Answer
Answer: c [Reason:] Fibres possess highest tensile strength in comparison to other polymers.
9. Which of the following kind of polymers are known for their high crystallinity?
a) isotactic
b) syndiotactic
c) atactic
d) none of the mentioned
Answer
Answer: a [Reason:] There is high steric regularity in isotactic polymers which fosters close packing of molecular chains. Thus, they are highly crystalline.
10. Which of the following category does cellulose nitrate fall into?
a) natural
b) synthetic
c) semi-synthetic
d) none of the mentioned
Answer
Answer: c [Reason:] Cellulose nitrate is a chemically modified form of cellulose. That’s why it falls under the category of semi-synthetic polymers.
11. The polymer in which steric placements of the substituent are arranged in such a way to give alternate d and l configurations, is known as _________________
a) isotactic polymer
b) atactic polymer
c) syndio-tactic polymer
d) none of the mentioned
Answer
Answer: c [Reason:] Syndio-tactic sequence represents alternate d and l configurations, thus shows a good tendency to crystallize.
Set 3
1. Which of the following reaction is not accompanied by elimination of a byproduct molecule?
a) addition polymerization
b) condensation polymerization
c) both of the mentioned
d) none of the mentioned
Answer
Answer: a [Reason:] In condensation polymerization, the molecules undergo condensation reaction with a release of a byproduct molecule like water, HCl, etc.
2. The chain growth process is usually much slower than the step-growth process. State true or false.
a) true
b) false
Answer
Answer: b [Reason:] The step-growth process is usually slower than addition reaction as it proceeds by an equilibrium step mechanism.
3. How does the monomer conversion vary at the early stage of step-growth polymerization?
a) faster
b) slower
c) steady
d) none of the mentioned
Answer
Answer: a [Reason:] The monomer molecules disappear a faster rate in the early stages of step polymerization.
4. The process in which the molecular weight of polymer almost remains unchanged with the progress of reaction is a ___________
a) addition polymerization
b) condensation polymerization
c) copolymerization
d) none of the mentioned
Answer
Answer: a [Reason:] The molecular weight of polymer remains more or less unchanged with increasing conversion whereas molecular weight increases throughout the step-growth process.
5. What does the reaction mixture of addition polymerization contain at any instant of time?
a) full grown polymer molecules
b) unreacted monomer molecules
c) free radical chains and initiators
d) all of the mentioned
Answer
Answer: d [Reason:] At any instant of time, the reaction mixture consists of polymer molecules, unreacted monomers and a very little concentration of free radical chains and initiators.
6. Which of the following polymers contains −C−C− linkages only?
a) addition polymers
b) condensation polymers
c) copolymers
d) none of the mentioned
Answer
Answer: a [Reason:] Chain growth polymers contain only −C−C− linkages whereas step growth polymers contain atoms like O, N, S in between the −C−C− linkages.
7. Which of the following polymerization can be carried out in melt condition or in solution state?
a) addition polymerization
b) condensation polymerization
c) both of the mentioned
d) none of the mentioned
Answer
Answer: c [Reason:] Addition and Condensation polymerization, both can be accomplished in bulk under melt condition or in solution.
8. The process in which molecular weight control is achieved by using a stoichiometric imbalance of the reacting functional group is ___________
a) chain growth process
b) step growth process
c) substitution process
d) none of the mentioned
Answer
Answer: b [Reason:] Control of molecular weight in condensation polymerization is accomplished by the use of stoichiometric imbalance of the reacting functional group or a calculated amount of monofunctional monomer.
9. Fully grown polymers are formed at the incidence of termination reaction in addition polymerization reaction. State true or false.
a) true
b) false
Answer
Answer: a [Reason:] In an addition polymerization reaction, with the incidence of termination reaction, fully grown polymer called dead polymer is formed.
10. Which reaction may allow the biphasic interfacial polymerization technique?
a) addition polymerization
b) condensation polymerization
c) both of the mentioned
d) none of the mentioned
Answer
Answer: b [Reason:] Condensation polymerization can be accomplished by employing biphasic interfacial polymerization technique.
Set 4
1. What is the size of the monomer droplets in suspension polymerization?
a) 25-30 mm
b) 0.1-5 mm
c) 15-20 mm
d) 50-60 mm
Answer
Answer: b [Reason:] The size of the monomer droplets is generally in the range of 0.1-5 mm.
2. Which of the following feature of water as a solvent helps in purity of polymer?
a) low cost
b) non-toxic nature
c) convenient boiling temperature
d) zero chain transfer constant
Answer
Answer: d [Reason:] The special feature of water as a solvent is that it provides us with a medium characterized by zero chain transfer constant.
3. Which of the following compounds can minimize the fluctuations in surface tension of emulsion in emulsion polymerization?
a) soaps
b) cetyl alcohol
c) dextrin
d) peroxides
Answer
Answer: b [Reason:] Cetyl alcohol plays the role of a surface tension regulator and minimizes the fluctuations in the emulsion as the polymerization progresses.
4. Which of the following compounds is used to control the polymer chain length in emulsion polymerization?
a) cetyl alcohol
b) buffer solutions
c) dodecyl mercaptan
d) gelatin
Answer
Answer: Dodecyl mercaptan is used as a chain length regulator or chain transfer agent of high transfer constant to control the chain length of the polymer.
5. Which of the following cannot be a protective colloid for emulsion polymerization?
a) Carboxymethyl cellulose
b) Cetyl alcohol
c) gelatin
d) poly vinyl alcohol
Answer
Answer: b [Reason:] The water soluble polymers like carboxy-methyl cellulose, PVA and gelatin stabilizes the emulsion and prevents emulsion break down with progress of polymerization, so these can be called as a protective colloid for emulsion.
6. How is the polymerization rate in emulsion polymerization dependent on the rate of radical generation?
a) directly proportional
b) inversely proportional
c) no dependence
d) cannot be determined
Answer
Answer: c [Reason:] The polymerization rate per cubic centimeters of aqueous phase is given by- Rp= kp (N/2)[M]
Thus the rate Rp is independent of rate of radical generation, Ri.
7. How is the rate of polymerization affected with the change in surfactant concentration in emulsion polymerization?
a) increases with increase in concentration
b) decreases with increase in concentration
c) no effect
d) cannot be determined
Answer
Answer: a [Reason:] The rise in surfactant concentration increases the number of polymer formed per cubic centimeters of the aqueous phase, which consequently increases the rate of polymerization rate, as the polymerization rate is given by-
Rp= kp (N/2)[M].
8. How is the degree of emulsion polymerization related to the monomer concentration, [M] and the rate of radical generation, Ri?
a) directly proportional to [M], inversely proportional to Ri
b) inversely proportional to Ri, directly proportional to [M].
c) directly proportional to Ri, independent of [M].
d) directly proportional to [M], independent of Ri
Answer
Answer: a [Reason:] The degree of polymerization is given by-
Xn = Ʋp/Ʋi = kpN[M]/Ri
So, clearly the degree of emulsion polymerization is proportional to first power of [M] and negative first power of Ri.
9. Which of the following polymerization technique allows the increase in both the rate and degree of polymerization simultaneously by increasing a certain parameter?
a) bulk polymerization
b) solution polymerization
c) suspension polymerization
d) emulsion polymerization
Answer
Answer: d [Reason:] The emulsion polymerization technique allows the increase in both the rate and degree of polymerization simultaneously by increasing the number of polymer particles, N at a fixed rate of initiation.
10. What is the average equilibrium radical concentration in the aqueous medium in emulsion polymerization?
a) 108 radical/cm3
b) 1013 radical/cm3
c) 105 radical/cm3
d) 1015 radical/cm3
Answer
Answer: a [Reason:] The equilibrium radical concentration in the aqueous medium, [Raq∙] is measured to be about 108 radical/cm3.
Set 5
1. A rubber polymer sample A is reacted with chromic acid solution and yields acetic acid solution. Compound A also gives positive Weber test. Which of the following is possibly A?
a) 1,4-polyisoprenes
b) butyl rubber
c) nitrile butadiene rubber
d) all of the mentioned
Answer
Answer: a [Reason:] 1,4-polyisoprenes yield acetic acid with chromic acid solution which is identified by its odour. It also gives positive weber test.
2. Which of the following does not give positive weber test of rubbers?
a) natural rubber
b) butyl rubber
c) polyisoprene rubber
d) styrene butadiene rubber
Answer
Answer: d [Reason:] In weber test, acetone-extracted polymer is dissolved in carbon tetrachloride with little bromine solution and then heated to remove excess bromine. The residue is then warmed in little phenol. The solution turns violet or purple due to presence of poluisoprenes, and so his test is positive for NR, IR and butyl rubber.
3. Polysulphide rubbers when treated with trichloroacetic acid imparted colour X, which turned to colour Ysolution on boiling and then colour Z precipitate on dilution. Which set of colours represent X, Y, Z, respectively?
a) pink, red-brown, grey
b) pink, ruby-red, rose-pink
c) pink, red-brown, yellow
d) pink, ruby-red, yellow
Answer
Answer: b [Reason:] Polusulphide rubbers give pink colour on treatment with trichloroacetic acid which turns ruby-red solution on boiling, giving rose-pink precipitate on dilution.
4. Which of the following rubbers when treated with trichloroacetic acid give pink-mauve melt and on dilution give grey-mauve precipitate?
a) isomerized rubber
b) acetone-extracted NR
c) gutta percha
d) all of the mentioned
Answer
Answer: d [Reason:] Acetone-extracted NR, isomerizaed rubber and gutta percha when warmed with trichloroacetic acid give pink-mauve melt and on dilution with water result in grey-mauve precipitate.
5. Which of the following rubber do not respond to trichloroacetic acid?
a) isomerized rubber
b) chlorinated rubber
c) polysulphide rubber
d) butyl rubber
Answer
Answer: b [Reason:] Chlorinated rubber does not produce any effect when treated with trichloroacetic acid.
6. A strip of filter paper dissolved in ethereal solution containing p-dimethylamino benzaldehyde and hydroquinone and then moistened with a 30% solution of trichloroacetic acid in isopropanol produces blue-violet colour in the presence of pyrolytic vapours of rubbers A and B. Which of the following pair represent rubbers A and B?
a) natural rubber and butyl rubber
b) styrene butadiene rubber and silicone rubber
c) styrene butadiene rubber and natural rubber
d) natural rubber and nitrile butadiene rubber
Answer
Answer: a [Reason:] The pyrolytic vapours of natural rubber and butyl rubber both produce deep-blue or blue-violet colour to the paper.
7. Which of the following rubbers turn the filter paper in ethereal solution containing p-dimethylamino benzaldehyde and hydroquinone and then moistened with a 30% solution of trichloroacetic acid in isopropanol grey with a yellow tinge?
a) natural rubber
b) silicones
c) polychloroprenes
d) butyl rubbers
Answer
Answer: c [Reason:] The pyrolytic vapours of polychloroprenes turn the filter paper grey with a yellow tinge.
8. What colour is obtained by the pyrolytic vapours of butyl rubber on the filter paper freshly soaked in a solution obtained by dissolving yellow mercuric oxide in conc. sulphuric acid and water on boiling?
a) bright yellow
b) grey
c) blue
d) brown-yellow
Answer
Answer: a [Reason:] Pyrolytic vapours of butyl rubber produce a bright yellow colour on filter paper freshly soaked in a solution obtained by dissolving yellow mercuric oxide in conc. sulphuric acid and water on boiling.
9. Which of the following do not respond to the Molisch test for carbohydrates?
a) cellulose acetate
b) viscose rayon
c) cellulose nitrate
d) none of the mentioned
Answer
Answer: c [Reason:] Cellulose acetate and viscose rayon both give purple colour when Molisch test is performed to them. Cellulose nitrate does not respond to this test at all.
10. What colour is obtained when a drop of diphenylamine solution in concentrated sulphuric acid is added to the sample of cellulose nitrate in the absence of other oxidizing agents?
a) deep blue
b) yellow
c) grey
d) red
Answer
Answer: a [Reason:] A deep blue colour product is obtained when a drop of diphenylamine solution in concentrated sulphuric acid is added to the sample of cellulose nitrate in the absence of other oxidizing agents.
11. The aqeous extracts of some polymers when tested with chomotropic solution followed by addition of sulphuric acid and then heating to nearly 100 C gave dark violet colour. Which of the following cannot respond to this test?
a) polyvinyl formal
b) polyoxymethylenes
c) urea-formaldehyde resisns
d) polyacrylonitrile
Answer
Answer: d [Reason:] The polymers containing or liberating formaldehyde can turn the solution dark violet. Thus, polyacrylonitrile does not respond to this test.
12. What colour is obtained if condensed pyrolyzate of polyacrylonitrile is made alkaline and boiled with ferrous sulphate followed by acidification?
a) ruby-red
b) prussian blue
c) bright blue
d) red-brown
Answer
Answer: b [Reason:] Prussian blue precipitate is obtained on the treatment of pyrozylate of polyacrylonitrile.
13. A strip of cupric acid paper, freshly moistened with a dilute solution of benzidine in dilute acetic acid is held in the pyrolytic vapours of polymer A and a bright blue colouration is obtained. Which of the following could be polymer A?
a) polyamide
b) polyacryonitrile
c) butyl rubber
d) polyvinyl formal
Answer
Answer: b [Reason:] Pyrolytic vapours of polyacrylonitrile respond to this test and develop bright blue colouration.
14. What colour is obtained when a strip of filter paper soaked in saturated solution of o-nitrobenzaldehyde in dilute NaOH is held over the prylotic vapours of Nylon 6,6?
a) grey
b) black
c) red
d) yellow
Answer
Answer: b [Reason:] The pyrolytic vapours of Nylon 6,6 gives mauve-black colour, when a strip of filter paper soaked in saturated solution of o- nitrobenzaldehyde in dilute NaOH is brought near it.
15. Which of the following polymer will not give grey colour when their pyrolytic vapours are tested with a strip of filter paper soaked in saturated solution of o- nitrobenzaldehyde in dilute NaOH?
a) Nylon 6
b) Nylon 66
c) Nylon 12
d) Nylon 11
Answer
Answer: b [Reason:] This test is positive only for the polyamides containing diacids other than adipic acid. Nylon 66 contains adipic acid.
Total Views: 16
