GATE XE year:2019 PYQs & Answers — Page 13

Questions 121–130 of 175. Imported answers require independent review unless marked reviewed.

Match the following products to the most suitable polymer for their manufacture:

Product P. Electrical cables Q. Electrical switches R. Optical lenses S. Shoe soles

Polymer

Polyurethane

Poly(methyl methacrylate)

Cross-linked polyethylene

Phenol formaldehyde resin

Your answerChoose one option.

P-3, Q-2, R-1, S-4

P-3, Q-4, R-2, S-1

P-4, Q-3, R-1, S-2

P-2, Q-3, R-1, S-4

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The order of limiting oxygen index for the following polymers is (polypropylene=PP; PTFE=polytetrafluoroethylene; PVC=poly(vinyl chloride))

Your answerChoose one option.

PP < PTFE < Nylon 6 < PVC

PP < PVC < Nylon 6 < PTFE

PP < Nylon 6 < PVC < PTFE

PP < Nylon 6 < PTFE < PVC

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Match the following plastic additives to their function:

Additive P. Molybdenum disulfide Q. Glycerol monostearate R. Tribasic lead sulphate S. 2-Hydroxybenzophenone

Function

Heat stabilizer

UV-absorber

Antistatic agent

Solid layer lubricant

Your answerChoose one option.

P-3, Q-1, R-2, S-4

P-3, Q-4, R-1, S-2

P-4, Q-3, R-2, S-1

P-4, Q-3, R-1, S-2

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Match the material classification in Column A with the appropriate one in Column B: (PS=polystyrene, PPO=polyphenylene oxide, PDMS=poly(dimethyl siloxane), PP=polypropylene, PE=polyethylene, PP-g-MA=maleic anhydride grafted PP)

Column A P. Miscible blend Q. Immiscible blend R. Compatibilized blend S. Polymer composite

Column B

PDMS + fumed silica

Nylon 6 + PP-g-MA + PP

PS + PPO

PE + PP

Your answerChoose one option.

P-3, Q-4, R-2, S-1

P-4, Q-3, R-2, S-1

P-3, Q-4, R-1, S-2

P-4, Q-3, R-1, S-2

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A linear amorphous polymer has a T_g of +10 °C. At 28 °C, it has a melt viscosity of 4 × 10⁸ poise. The viscosity of the polymer at its T_g is ______ × 10¹³ poise (round off to one decimal place).

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A polypropylene (PP) bar with a 10 mm × 10 mm square section is 225 mm long. The modulus of PP bar is 861 MN m⁻². It is pinned at both ends and an axial compressive load of 140 N is applied. The strain due to the applied load experienced by the PP bar is ____ % (round off to two decimal places).

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In a unidirectional carbon fibre/vinyl ester composite, the ratio of the moduli of the carbon fibre to that of vinyl ester is 35 and the fibres take up 50% of the cross-section. The percentage of applied force taken up by the fibres is ______ % (round off to one decimal place).

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A 3 mm thick layer of softened poly(methyl methacrylate) at 190 °C is sandwiched between two flat parallel plates. A shear stress of 100 kPa is applied to the softened polymer. Assuming the softened polymer as a Newtonian fluid with an apparent viscosity of 3.9 × 10⁴ Pa s, the relative sliding velocity between the two plates is ____ mm s⁻¹ (round off to one decimal place).

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For ABN initiated polymerization of styrene, if both the monomer and initiator concentration are doubled, then the rate of polymerization increases by a factor of ______ (round off to two decimal places).

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If 49 moles of hexamethylene diamine is reacted with 50 moles of adipic acid to prepare Nylon 66, then the number average molecular weight, M̅_n of the resulting polymer at 99.5% conversion (ignoring contribution from end groups) is ______ g mol⁻¹ (round off to 2 decimal places).

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GATE XE year:2019 PYQs

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21