mechanical engineering MCQs – Page 52

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

2551. Natural uranium is made up of__________________?
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A. 99.282% U234, 0.712% U238, 0.006% U235

B. 99.282% U238, 0.712% U235, 0.006% U234

C. 99.282% U235, 0.712% U238, 0.06% U234

D. 99.282% U235, 0.712% U234, 0.006% U238

E. none of the above

2552. A reactor capable of converting a ferrite material into fissile isotopes is called____________________?
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A. boiling water reactor

B. fast breeder reactor

C. regenerative reactor

D. breeder reactor

E. ferrite reactor

2553. Electron-volt is the unit of________________?
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A. there is no such unit.

B. energy

C. atomic power

D. radio activity

E. voltage

2554. In boiling water reactor, moderator is__________________?
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A. graphite rod

B. ferrite rod

C. coolant itself

D. blanket of thorium

E. liquid sodium metal

2555. For economical operation of a nuclear plant__________________?
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A. reflector should be used

B. used fuel should be reprocessed

C. coolant should be employed

D. moderator should be used

E. control rods should be used

2556. The ultimate tensile strength and yield strength of most of the metals, when temperature falls from 0 to l00C will _________________?
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A. decrease

B. remain same

C. show unpredictable behaviour

D. increase

E. first increase and then decrease

2557. The unique property of cast iron is its high ___________________?
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A. ductility

B. hardness

C. damping characteristics

D. malleability

E. surface finish

2558. A reversible change in the atomic structure of steel with corresponding change in the properties is known as___________________?
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A. molecular change

B. allotropic change

C. atomic change

D. solidus change

E. physical change

2559. Malleability of a material can be defined as ______________________?
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A. all of the above

B. ability to undergo large permanent deformations in compression

C. none of the above

D. ability to undergo large permanent deformations in tension

E. ability to recover its original form

2560. The ability of a material to resist softening at high temperature is known as____________________?
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A. creep

B. hot hardness

C. superhardening

D. hot tempering

E. fatigue

2561. Points of arrest for iron correspond to__________________?
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A. stages at which properties do not change with increase in temperature

B. there is nothing like points of arrest

C. none of the above

D. stages at which further heating does not increase temperature for some time

E. stages at which allotropic forms change
2562. The crystal of alpha iron is ____________________?
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A. cubic structure

B. hexagonal close packed

C. orthorhombic crystal

D. body centred cubic

E. face centred cubic

2563. Isotropic materials are those which have the same ____________________?
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A. stresses induced in all directions

B. density throughout

C. elastic properties in all directions

D. thermal properties in all directions

E. electric and magnetic properties in all directions

2564. Stress relaxation is- the phenomenon ___________________?
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A. none of the above

B. in which stress remains constant on in-creasing load

C. stress reduces on increasing load

D. in which parts are not loaded

E. in which deformation tends to loosen the joint and produces a stress reduced
2565. Ferromagnetic alpha iron exists in temperature range of________________?
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A. below 723C

B. 1400-1539C

C. 910-1440C

D. above 1539C

E. 770 910C

2566. A material is known as allotropic or polymorphic if it __________________?
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A. has its atoms distributed in a random pattern

B. none of the above

C. responds to heat treatment

D. has a fixed structure under all conditions

E. exists in several crystal forms at different temperatures
2567. The percentage of carbon in grey iron castings usually varies between __________________?
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A. 5 7%

B. 1 2%

C. 7-9%.

D. 2.5 to 4.5%

E. 0.5 to 1%

2568. Mild steel belongs to the following category___________________?
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A. low carbon steel

B. special steel

C. high carbon steel

D. medium carbon steel

E. alloy steel

2569. For the allotropic forms of iron, the points of arrest are __________________?
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A. the points where major changes take place

B. constant for all metals

C. the points of discontinuity

D. the points where no further change oc-curs

E. the points where there is no further flow of metal

2570. Which of the following constituents of steels is softest and least strong ________________?
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A. cementlte

B. ferrite

C. bainite

D. austenite

E. pearlite

2571. In grey cast iron, carbon is present in the form of____________________?
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A. flakes

B. free carbon

C. nodular aggregates of graphite

D. cementite

E. spheroids

2572. The temperature at which ferromagnetic alpha iron transforms to paramagnetic alpha iron is _______________?
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A. 1050C

B. below recrystallisation temperature

C. above recrystallization temperature

D. 910C

E. 770C
2573. The loss of strength in compression with simultaneous gain in strength in tension due to overloading is known as________________?
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A. visco elasticity

B. hysteresis

C. creep

D. inelasticity

E. Boeschinger effect
2574. Blast furnace produces following by reduction of iron ore_______________?
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A. white iron

B. pig iron

C. malleable iron

D. wrought iron

E. cast iron

2575. Machining properties of steel are improved by adding___________________?
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A. chromium, nickel

B. lubricants

C. sulphur, lead, phosphorous

D. silicon, aluminium, titanium

E. vanadium, aluminium

2576. Which is false statement about tempering. Tempering is done to_______________?
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A. improve machinability

B. release stresses

C. reduce hardness and brittleness

D. improve ductility

E. improve toughness

2577. Which of the following pipes is least corrosion resistant__________________?
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A. mild steel

B. wrought iron

C. cast iron

D. copper

E. brass

2578. The hardness of steel increases if it contains____________________?
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A. pearlite

B. martensite

C. all of the above

D. cementite

E. austenite

2579. Permalloy is a___________________?
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A. kind of stainless steel

B. none ferrous alloy

C. nickel and iron alloy having high permeability

D. cutting tool material

E. polymer

2580. Aluminium bronze contains__________________?
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A. 90% magnesium and 9% aluminium with some copper

B. 92.5% aluminium, 4% copper, 2% nickel, and 1.5% Mg

C. 10% aluminium and 90% tin

D. 10% aluminium and 90% copper

E. 94% aluminium, 4% copper and 0.5% Mn, Mg, Si and Fe

2581. An important property of high silicon (12 18%) cast iron is the high__________________?
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A. brittleness

B. corrosion resistance

C. plasticity

D. tenacity

E. hardness
2582. Age-hardening is related with______________?
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A. german silver

B. duralumin

C. gun metal

D. cast iron

E. stainless steel

2583. The hardness of steel primarily depends on _____________________?
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A. shape of carbides and their distribution in iron

B. heat treatment employed

C. method of manufacture

D. %age of alloying elements

E. %age of carbon

2584. Hardness of upper bainite (acicular structure) is about___________________?
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A. RC 48

B. RC 32.

C. RC 65

D. RC 57

E. RC 80

2585. Surveying tapes are made of a material having low coefficient of expansion and enough strength. The alloy used is__________________?
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A. invar

B. duralumin

C. silver metal

D. monel metal

E. Hastelloy

2586. Amorphous material is one___________________?
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A. in which there is no definite atomic structure and atoms exist in a random pattern just as in a liquid

B. none of the above

C. in which atoms align themselves in a geometric pattern upon solidification

D. which emits fumes on melting

E. which is not attacked by phosphorous

2587. Which is false statement about properties of aluminium ___________________?
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A. corrosion resistance is good

B. fatigue strength is not high

C. modulus of elasticity is fairly low

D. wear resistance is very good

E. creep strength limits its use to fairly low temperatures

2588. Basic solution is one which has pH value___________________?
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A. equal to 7

B. pH value has nothing to do with basic solution

C. less than 7

D. greater than 7

E. none of the above

2589. The alloy used for making electrical resistances and heating elements is____________________?
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A. magnin

B. peiminvar

C. nichrome

D. elinvar

E. invar

2590. The percentage of carbon in pig iron varies from___________________?
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A. 0.1 to 1.2%

B. 4 to 4.5%

C. 4.5 to 6.3%.

D. 2.5 to 4%

E. 1.5 to 2.5%

2591. Pick up the wrong statement Nickel and chromium in steel help in _________________?
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A. providing high strength at elevated temperatures

B. improving machining properties

C. raising the elastic limit

D. improving the resilience and ductility

E. providing corrosion resistance

2592. Vanadium in high speed steels__________________?
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A. forms very hard carbides and thus in-creases wear resistance

B. provides high hot hardness

C. promotes decarburisation

D. promotes retention of austenite

E. increases toughness

2593. White cast iron contains carbon in the form of__________________?
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A. cementite

B. graphite

C. free carbon

D. white carbon

E. ferrite

2594. A reversible change in the atomic structure of the steel with a corresponding change in the properties is known as_________________?
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A. precipitation

B. allotropic change

C. recrystallisation

D. heat treatment

E. austempering

2595. By severely deforming a metal in a particular direction it becomes _________________?
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A. homogeneous

B. ductile

C. malleable

D. anisotropic

E. isotropic

2596. Recrystallisation temperature can belowered by_________________?
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A. all of the above

B. grain refinement

C. none of the above

D. purification of metal

E. working at lower temperature

2597. Lead is poured into the joint between two pipes. These pipes may be made of____________________?
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A. asbestos cement

B. concrete

C. vitrified clay

D. mild steel

E. cast iron
2598. The percentage of carbon in low carbon steel is__________________?
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A. 0.15%

B. 0.7%.

C. 0.05%

D. 0.30%

E. 0.50%

2599. Babbit metal is a_________________?
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A. A. and C. above

B. tin base alloy

C. lead base alloy

D. copper base alloy

E. all of the above

2600. Wrought iron is________________?
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A. least resistant to corrosion

B. high in strength

C. heat treated to change its properties

D. highly resistant to corrosion

E. hard