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Current Affairs January 2024

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Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.

A. 10-3

B. 103

C. 10-15

D. 1015

Correct Answer :

A. 10-3


Related Questions

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A polymer is termed as an 'elastomer', if its percentage elongation is more than 100%. An elastomer is termed as 'rubber' if its percentage elongation is more than __________ percent.

A. 150

B. 200

C. 300

D. 400

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__________ is used for tying the steel columns to concrete foundation.

A. Grouting

B. Eyebolt

C. Anchor bolts

D. Refractory castables

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Which of the following is a commonly used manometric liquid for low pressure range?

A. Ethyl alcohol

B. Carbon tetrachloride

C. Glycerol

D. Ethylene glycol

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__________ test is the appropriate test to determine whether a material is ductile or brittle.

A. Impact

B. Cupping

C. Hardness

D. Tensile

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Identify the correct statement.

A. Sphlerite is zinc oxide

B. The first law of the thermodynamics is stated as δE = δQ - δW

C. Lead can be produced in a blast furnace

D. T. ferrooxidans is a fungus that can be used for leaching chalcopyrite

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Sacrificial anode method is used in the protection of pipelines which are buried underground. Sacrificial anode

A. Occurs higher in the electro-chemical series of metals

B. Is exemplified by magnesium plate

C. Is much cheaper than the cathodic base material to be guarded against corrosion

D. All (A), (B) & (C)

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X-rays are

A. Positively charged

B. Negatively charged

C. Neutral

D. Of higher wavelength than visible light

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Elimination of brittleness resulting from welding of saw blades is done by __________ of the welded portion.

A. Annealing

B. Toughening

C. Work hardening

D. Tempering

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Thermit welding is categorised as the __________ welding.

A. Forge

B. Fusion

C. Resistance

D. Arc

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A material in which the atoms are arranged regularly in some directions but not in others, is termed as 'mesomorphous material'; an example of which is

A. Lead

B. Glass

C. Mica

D. Silver

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__________ is the hardest oxide and is hence used where high wear resistance at high temperature is required.

A. Beryllium

B. Zirconia

C. Alumina

D. Magnesia

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4

Spherical shape of mercury droplets is due to its

A. High viscosity

B. Low surface tension

C. High density

D. High surface tension

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In a boundary layer developed along the flow, the pressure decreases in the downstream direction. The boundary layer thickness in this case will

A. Decrease gradually

B. Increase gradually

C. Increase rapidly

D. Remain constant

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The wet bulb temperature is lower in dry air than in wet air at the same temperature. A dry bulb thermometer registers a higher temperature than a wet bulb thermometer except at __________ percent relative humidity.

A. 0

B. 100

C. 50

D. None of these

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A thin, flat & square plate measuring 2 m × 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is __________ W/m2 °C.

A. 50

B. 100

C. 150

D. 200

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In troposphere (the weather domain), the temperature 't' at height 'h' above the sea level in metres is given by (where, temperature at sea level is 15°C and t is in °C.)

A. t = 15 - 0.0065 h

B. t = 15 + 0.0065 h

C. t = 0.0035 h - 15

D. t = 15 - 0.0035 h

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Wave length of X-rays is about 1 angstrom; however it cannot pass through a sheet of

A. Paper

B. Cloth

C. Lead

D. Aluminium

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Wood is a/an __________ material.

A. Amorphous

B. Cellular

C. Homogeneous

D. Granular

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Window panes of aeroplanes are normally made of

A. Perspex (PMMA)

B. Teflon (PTFE)

C. Bakelite (phenol formaldehyde)

D. Polystyrene

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4

Hot working of lead is carried out at

A. 75°C

B. 373°K

C. 150°C

D. Room temperature

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4

The starting of a car takes time in winter, because the

A. Octane number of fuel is decreased

B. Fuel supply for ignition is not sufficient

C. Vaporisation of the fuel is decreased

D. Pour point of fuel decreases

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Presence of nickel & chromium in steel does not raise its

A. Elastic limit

B. Machining properties

C. Ductility

D. Resilience

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Materials having resistivity ranging from 1 to 100 ohm. cm is termed as

A. Conductor

B. Insulator

C. Semi-conductor

D. None of these

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Hot dipping process is used for coating a low melting point metal (e.g. Pb, Sn, Zn) on iron, steel & copper having relatively higher melting points. Which of the following is not a hot dipping process?

A. Galvanising

B. Tinning

C. Sherardizing

D. None of these

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__________ wire is never used for making the heating element.

A. Nichrome

B. Kanthal

C. Invar

D. None of these

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Filler material used in welding should have __________ as compared to the parent metal to be welded.

A. Lower melting temperature

B. Same melting temperature

C. Same composition

D. Both 'b' & 'c'

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Addition of __________ to steel does not help in improving its machinability.

A. Sulphur

B. Silicon

C. Lead

D. Phosphorous

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Calorific value of __________ are almost same.

A. Lignite & anthracite coal

B. Lignite & coal gas

C. Petrol & diesel

D. Coal gas & natural gas

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Joining of thin foils is preferred to be done by

A. Gamma rays

B. X-rays

C. Microwaves

D. Gas welding

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Limestone is added in the blast furnace (during pig iron manufacture) to

A. Form slag by combining with impurities

B. Supply heat by undergoing exothermic reaction with impurities

C. Reduce the coke consumption

D. Reduce slag viscosity