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While the recrystallisation temperature for pure metals is 0.3 Tm, the same for alloys is equal to __________ × Tm (where, Tm Melting temperature).

A. 0.25

B. 0.45

C. 0.70

D. 0.95

Correct Answer :

C. 0.70


Related Questions

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In case of water (Prandtl number ≈ 6) flowing over a flat plate heated over the entire length, the thermal boundary layer thickness as compared to hydrodynamic boundary layer thickness is

A. Less

B. More

C. Equal

D. Unpredictable

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Faraday's law of electrolysis is related to the

A. Cation speed

B. Atomic number of the cation

C. Equivalent mass of the electrolyte

D. None of these

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4

Which of the following contributes maximum as main source of sulphur in the blast furnace charge?

A. Sinter

B. Coke

C. Iron ore

D. Limestone

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Wohler test is a destructive test to find out the __________ strength of a prepared metal specimen.

A. Creep

B. Fatigue

C. Endurance

D. Tensile

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Broaching tools are usually made of

A. Cermets

B. High speed steel

C. Tungsten carbide

D. Stellite

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Silicon percentage in acid resistant cast iron is about

A. 4

B. 8

C. 14

D. 20

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Drossing is a __________ operation.

A. Smelting

B. Dressing

C. Roasting

D. Dressing

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The main reducing agent in iron blast furnace is

A. Carbon dioxide

B. Carbon monoxide

C. Oxygen

D. Air

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Which of the following does not have a sharp melting point?

A. Thoria

B. Glass

C. Ice

D. Pig iron

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Wrought iron is never shaped by

A. Casting

B. Cold working

C. Forging

D. Welding

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The cathode in an electrochemical cell always carries

A. Negative charge

B. Positive charge

C. Zero charge

D. Positive or negative charge depending upon the nature of the cell

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Strain hardening effect in metals subjected to cold working is due to the __________ mechanism.

A. Slip

B. Fracture

C. Winning

D. Dislocation

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Removal of non-condensable from steam or other vapour is termed as the __________ process.

A. Condensation

B. Deaeration

C. Scavenging

D. Exhaust

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The order of a chemical reaction

A. Can be determined only experimentally

B. Can be determined from the stoichiometry of the reaction

C. Cannot be zero

D. Can be fractional

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Though tin occurs lower than iron in the electrochemical series, yet it is coated on steel for corrosion protection, because of its

A. Lower cost

B. Abundant availability

C. Resistance to vegetable acids as the tin plate are commercially used in 'canning' industry

D. None of these

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Case hardening is not done by

A. Nitriding

B. Hot dipping

C. Electroplating

D. Both b & c

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4

Half life of a radioactive isotope corresponds to the time required for half of the __________ to decay.

A. Atoms

B. Neutrons

C. Nucleons

D. Electrons

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4

Maximum change in the hardness of martensite occurs in the carbon content range of __________ percent in steel.

A. 0.01 to 0.10

B. 0.2 to 0.4

C. 0.5 to 0.7

D. 0.8 to 1.0

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4

Titanium is added to molten aluminium alloys before casting for the purpose of

A. Grain refinement

B. Increasing corrosion resistance

C. Reducing porosity

D. Improving fluidity

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Dislocations are __________ defects.

A. Point

B. Line

C. Volume

D. None of these

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Routing in production, planning & control is concerned with the

A. Sequence of operation to be performed

B. Progress of work performed

C. Authorisation of work to be performed

D. Balancing of load on machines

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Bad odour in sanitary latrines is reduced by periodically sprinkling

A. Bleaching powder

B. Lime powder

C. Aluminium sulphate

D. None of these

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Minimum temperature upto which water can be theoretically cooled down in the cooling tower by evaporative cooling is equal to the __________ temperature of air.

A. Wet bulb

B. Dry bulb

C. Saturation

D. Dew point

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Increasing sulphur content in pig iron tends to make it

A. Soft

B. Hard

C. Tough

D. Ductile & malleable

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4

Work hardenable alloy steel used to make the bucket wheel excavators, blades of bulldozers and other earth moving equipments contain iron, carbon and

A. Manganese

B. Silicon

C. Nickel

D. Chromium

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Most important property of steels for use in automobile bodies is the

A. Formability

B. Yield strength

C. Toughness

D. Resilience

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Consideration of the creep is the most important in case of the

A. Blades of gas turbine

B. Piston of an I. C. engine

C. Flywheel of steam engine

D. Cycle chain

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Electrolytic reduction cell used for conversion of calcined Al2O3 to Al is a carbon lined furnace operating at 800-900 °C. The purpose of electric current supplied to the furnace is to

A. Achieve very high purity of aluminium (99.9%)

B. Keep the electrolyte in liquid condition by the generation of heat

C. Electrolytically dissociate alumina

D. Both (B) & (C)

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4

Joule-Thomson co-efficient is the ratio of

A. Pressure change to temperature change occuring during adiabatic compression of a gas

B. Pressure change to temperature change occuring during adiabatic throttling of a gas

C. Temperature change to pressure change occuring during adiabatic compression of a gas

D. Temperature change to pressure change occuring during adiabatic throttling of a gas

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4

Air/fuel ratio by weight for combustion of methane with theoretical quantity of air will be about

A. 9 : 1

B. 17 : 1

C. 23 : 1

D. 29 : 1