GATE XE topic:engineering PYQs & Answers — Page 103

Questions 1021–1030 of 1772. Imported answers require independent review unless marked reviewed.

Topic practice 1772 questionsPage 103 of 178

A single screw extruder is operating at a rotational speed of 2 revolutions per second for the extrusion of a Newtonian polymer under open-discharge conditions (in absence of a die, the pressure drop,

= 0). The extruder has a screw diameter,

= 5 cm, a channel depth,

= 0.4 cm, distance between flights,

= 1 cm, and a helix angle,

= 20°. Assume the value of

= 3.14. The volumetric flow rate (rounded off to 2 decimal places) is ______ cm³/s.

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At 215 °C, the viscosity of a polystyrene of molecular weight 250 × 10³ g/mol is 8.0 × 10³ Pa s. The critical molecular weight of polystyrene,

= 35 × 10³ g/mol. For a similar polystyrene of molecular weight 500 × 10³ g/mol, the viscosity (rounded off to nearest integer) will be ______ × 10³ Pa s.

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There are two different PTFE polymer specimens of the following density (

) and % crystallinity. For PTFE- specimen-1,

is 2.144 g/cm³ and % crystallinity is 50. For PTFE- specimen-2,

is 2.215 g/cm³ and % crystallinity is 75. Assuming the polymer is pure and defect free, the density (rounded off to 3 decimal places) of 100% amorphous PTFE specimen will be ______ g/cm³.

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The behavior of a polymer is described by a Maxwell model consisting of a spring element of modulus 10¹⁰ Pa in series with a dashpot of viscosity 10¹² Pa s. In the solid, 50 s after the sudden application of a fixed strain of 1%, the stress (rounded off to 2 decimal places) will be ______ × 10⁷ Pa.

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A particular free radical polymerization process yields a polymer with a number average degree of polymerization,

= 100. The monomer concentration is doubled and the initiator concentration is increased by four times. Assuming that all rate coefficients and other parameters remain unchanged, the value of

(rounded off to the nearest integer) is ______.

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A polymer is synthesized from 2 moles of terephthalic acid (molecular weight of the repeat unit, (-OCC₆H₄CO-), is 132 g/mol), 1 mol of ethylene glycol (molecular weight of the repeat unit, (-OCH₂CH₂O-), is 60 g/mol), and 1 mol of butylene glycol (molecular weight of the repeat unit, (-O(CH₂)₄O-), is 88 g/mol). The reaction is terminated at 99% conversion of the acid. The number averaged molecular weight,

(rounded off to the nearest integer) is ______ g/mol.

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A sample of natural rubber (cis-1,4-polyisoprene) is vulcanized such that one of every 240 chain carbon atoms is cross-linked. The formula unit of the isoprene monomer is C₅H₈ (molecular weight = 68 g/mol). The average molecular weight (rounded off to the nearest integer) between cross-links is ______ g/mol.

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A sample of an oriented semi-crystalline polymer is subjected to uniaxial tensile stress,

, in an X-ray diffractometer. The wavelength of X-ray radiation (Cu K

) is

= 1.542 Å. The position of the (002) peak, which was found initially at a Bragg angle of 37.50° at

= 0 MPa shifted to 37.45° at

= 160 MPa. Assuming elastic deformation, the strain (rounded off to three decimal places) in the sample along the direction of applied stress is ______ × 10⁻³.

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In a typical bacterial growth curve, the first order kinetics for growth rate is observed in

Your answerChoose one option.

Lag phase

Log phase

Stationary phase

Death phase

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Which one of the following microorganism is NOT a causative agent for food borne diseases?

Your answerChoose one option.

Campylobacter jejuni

Clostridium perfringens

Norovirus

Borrelia burgdorferi

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GATE XE topic:engineering PYQs

Question 15

Question 16

Question 17

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Question 19

Question 20

Question 21

Question 22

Question 1

Question 2