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Current Affairs January 2024

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4

Powder metallurgy is used to produce

A. High precision components with complex cavities and sharp features

B. Components of large size

C. Porosity free components

D. Components of such alloys whose constituents do not form alloys readily

Correct Answer :

C. Porosity free components


Related Questions

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Constituents of stellite are

A. Zinc, copper & nickel

B. Cobalt, chromium & tungsten

C. Zinc, aluminium & nickel

D. Nickel, cobalt & vanadium

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4

Lead is poured into the joint between two- __________ pipes.

A. Mild steel

B. Concrete

C. Cast iron

D. Asbestos cement

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4

The emf of a Deniell cell Zn | Zn2+ || Cu2+ | Cu can be increased by

A. Decreasing the surface area of the electrodes

B. Increasing the concentration of zinc sulphate solution

C. Increasing the surface area of the electrodes

D. Increasing the concentration of copper sulphate solution

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4

A reduction in thermal resistance during heat transfer does not occur in the

A. Convection heat transfer by stirring the fluid and cleaning the heating surface

B. Conduction heat transfer by reduction in the material thickness and increase in the thermal conductivity

C. Radiation heat transfer by increasing the temperature and reducing the emissivity

D. None of these

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4

Pick out the wrong statement.

A. Geothermal energy is a non-conventional source of energy

B. Mass is converted into energy in both nuclear fission & fusion reaction

C. Inhalation of mercury vapour is not harmful for human beings

D. Inhalation of arsenic causes cancer

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4

A solid aluminium ball, when quenched in a water bath maintained at 40°C, cools down from 550°C to 450°C in 20 seconds. The expected temperature of the ball after next 20 seconds may be about __________ °C.

A. 370

B. 340

C. 320

D. 300

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4

Secondary hardening in steels arises out of the

A. Precipitation of fine alloy carbides at high temperatures

B. Refinement of ferrite grain size by working

C. Decomposition of retained austenite upon heat treatment

D. Precipitation of complex inter-metallic upon heat treatment

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4

The co-ordination number in simple cubic structure is

A. 4

B. 6

C. 8

D. 12

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4

Diameter of the rivet to be provided on a 20 mm. thick boiler plate will be __________ mm.

A. 10

B. 20

C. 30

D. 40

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4

Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of

A. Grashoff number

B. Grashoff number & Reynolds number

C. Reynolds number

D. Grashoff number & Prandtl number

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4

For a thermodynamic system undergoing a process, which of the following pairs best expresses the relationship similar to that expressed by the pressure volume plot?

A. Temperature - entropy

B. Temperature - pressure

C. Enthalpy - entropy

D. Enthalpy-pressure

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4

Specific gravity of hot metal (pig iron) is __________ times that of the blast furnace slag.

A. 2

B. 3

C. 0.8

D. 6

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4

Specific gravity of a metal, which weighs 5 kg in air and 4 kg when submerged in water, will be

A. 5

B. 1.25

C. 2.5

D. 3.75

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4

The elastic strain energy of a unit length of an edge dislocation as compared to that of a screw dislocation is

A. More

B. Equal

C. Less

D. Double

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4

A solar cell converts the sunlight directly into __________ energy.

A. Thermal

B. Electrical

C. Mechanical

D. Chemical

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4

Cascade control is

A. The continuous adjustment of the set point index of an automatic control loop by a primary (master) controller

B. Used when changes in process conditions cause serious upsets in the controlled variable

C. Useful to control flow from temperature

D. All 'a', 'b' & 'c'

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4

Which of the following is normally not found in both the S.I. (petrol) & C.I. (diesel) engines?

A. Air filter

B. Fuel injector

C. Exhaust silencer

D. Battery

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4

Out of the following, the __________ pipe has the least corrosion resistance.

A. Mild steel

B. Copper

C. Cast iron

D. Wrought iron

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4

CANDU type nuclear reactor using natural uranium as fuel is the extensively used nuclear reactor because of the fact that the

A. Specific fuel consumption is very low due to the use of heavy water

B. Fuel cost is much lower than that used in pressurised water or boiling water reactor

C. Heavy water is used both as coolant as well as moderator

D. Both 'b' & 'c'

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4

With increase in impurities in metals, their corrosion resistances

A. Increase

B. Decrease

C. Remain same

D. May increase or decrease; depending on the type of metal

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4

Mild steel has __________ crystal lattice structure.

A. Face centred cubic (fcc)

B. Body centred cubic (bcc)

C. Orthorhombic

D. Cubic

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4

Between 230 and 370°C, blue brittleness is caused in mild steel because of the

A. Immobility of dislocation

B. Strain-ageing

C. Increase in Young's modulus

D. Strain hardening

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4

Pick out the wrong statement.

A. Both annealing and normalising release the internal stresses of the material besides improving the mechanical properties

B. Low carbon steel does not respond to the heat treatment for hardening of the material, hence it is subjected to case hardening or surface hardening processes like cyaniding, carburising, nitriding etc., which produces high carbon outer layers resulting in increase of surface hardness

C. Induction hardening and flame hardening techniques are also used for surface hardening

D. Martempering of a material is a hardening process

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4

Which of the following is resistant to the action of both heat & chemicals?

A. Borosilicate glass

B. Silica glass

C. Soda lime glass

D. None of these

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4

Sub zero treatment of steel is done to

A. Suppress martensite transformation

B. Enhance its working performance in sub zero atmosphere

C. Reduce the retained austenite in hardened steel

D. Induce temper brittleness after its hardening

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4

All of the following alloying elements of steel increases hardness but sacrifice ductility, except

A. Nickel

B. Vanadium

C. Molybdenum

D. Chromium

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4

Referring to the periodic table of elements, it is found that with increasing atomic number. The atomic size in the same

A. Period increases

B. Period decreases

C. Group increases

D. Both 'b' & 'c'

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4

A jig is used while __________ a hole.

A. Boring

B. Counter boring

C. Drilling

D. Enlarging

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4

Two wires of the same radius & material having length in the ratio of 1 : 2 are stretched by the same force. The strain produced in the two wires will be in the ratio of

A. 1 : 1

B. 1 : 2

C. 2 : 1

D. 1 : 4

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4

The ability of tool steel to resist softening at high temperatures is termed as __________ hardness.

A. Red

B. Extended

C. Super

D. Extreme