mechanical engineering MCQs – Page 129

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 Review each marked answer and report any item that may be outdated or unclear.

mechanical engineering Mcqs

1. compressors gas turbines and jet engines 2. theory of machines 3. nuclear power plants 4. engineering materials 5. strength of materials mechanical engineering 6. thermodynamics 7. heat transfer 8. i c engines 9. steam boilers engines nozzles and turbines 10. engineering mechanics 11. fluid mechanics mechanical engineering 12. production technology 13. machine design 14. hydraulic machines 15. workshop technology 16. refrigeration and air conditioning

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____________________?
0

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__________________?
0

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

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