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Current Affairs January 2024

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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

Correct Answer :

D. Grashoff number & Prandtl number


Related Questions

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4

In the diving apparatus, helium is used along with oxygen, because it is

A. Easily available

B. Not soluble in blood at high pressure

C. Lighter than nitrogen

D. Completely miscible with oxygen

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4

Brinell Hardness Number (BHN) for talc is approximately in the range of

A. 1-5

B. 20-30

C. 100-150

D. 200-250

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4

__________ rubber is generally used for making 'O' rings used for vacuum sealings.

A. Natural

B. Neoprene

C. Butadiene

D. Nitrile

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4

Property responsible for the talcum powder to cling to the skin is the

A. Capillary action

B. Adhesion

C. Cohesion

D. Surface tension

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4

Triple point of water is

A. 0°F

B. 492°R

C. 0°K

D. -273°C

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4

Which of the following if present in iron ore, enhances its value?

A. Alumina

B. Alkali oxide

C. Lime & Magnesia

D. None of these

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4

Brittleness induced due to the presence of sulphur in steel can be reduced by adding

A. Manganese

B. Magnesium

C. Vanadium

D. Copper

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4

__________ wire is never used for making the heating element.

A. Nichrome

B. Kanthal

C. Invar

D. None of these

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4

Which of the following emissions in the exhaust gas of an I.C. engine causes the formation of photochemical smog?

A. Nitrogen oxides

B. Hydrocarbons

C. Both 'a' & 'b'

D. Carbon monoxide

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4

__________ is the most important element, which controls the physical properties of steel.

A. Manganese

B. Silicon

C. Carbon

D. Vanadium

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4

The phenomenon occurring during explosion of a hydrogen bomb is

A. Nuclear fission

B. Nuclear fusion

C. A combination of both nuclear fission & fusion

D. None of these

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4

Reduction in the grain size reduces the __________ of the material.

A. Fatigue resistance

B. Tensile strength

C. Creep resistance

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

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4

Quartz is a __________ material.

A. Diamagnetic

B. Ferromagnetic

C. Ferroelectric

D. Piezoelectric

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4

Sudden fall of atmospheric pressure by a large amount is an indication of the

A. Rain

B. Cold wave

C. Storm

D. Fair weather

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4

The main constituent of bones is

A. CaF2

B. Ca3(PO4)2

C. CaCO3

D. CaCl2

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4

A dummy activity is used in PERT network to describe the

A. Precedence relationship

B. Resource idleness

C. Resource restriction

D. Necessary time delay

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4

Photographic plates are coated with

A. Silver nitrate

B. Silver halide

C. Calcium silicate

D. Metallic silver

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4

For which pair of the fuel gases, calorific value (C.V.) of one fuel is almost double that of the other on volume basis (i.e., kcal/Nm3) while the C.V. is same on weight basis (i.e., kcal/kg)?

A. Propane and acetylene

B. Propane and LPG

C. Sewage gas and gobar gas

D. B.F gas and coke oven gas

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4

A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place

A. The better insulation material should be put just next to pipe (i.e., inside)

B. The better insulating material should be put outside

C. Either of the insulating material could be put on either side

D. Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)

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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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4

The cooling rate required to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours is __________ BTU/hr.

A. 100

B. 200

C. 1000

D. 2000

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4

Which of the following is an undesirable property of slag produced during the Pyrometallurgical method of metal extraction from its ore?

A. High fusibility & fluidity

B. High thermal conductivity

C. Low density

D. High chemical activity

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4

Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type

A. Parallel flow with equal heat capacities

B. Counter flow with equal heat capacities

C. Counter flow with unequal heat capacities

D. Parallel flow with unequal heat capacities

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4

Temperature profile along the length of a gasgas counter flow heat exchanger is correctly represented by

A.

B.

C.

D.

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4

Wavelength of radiation emitted by a body depends on the __________ of its surface.

A. Temperature

B. Area

C. Nature

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

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4

A form of stress corrosion failure termed as 'season cracking' is generally observed in

A. Thermosetting polymers

B. High carbon steels

C. Brasses

D. Borosilicate glasses

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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

The approximate height of a blast furnace having a useful volume of 2000 m3 is about __________ metres

A. 25

B. 35

C. 55

D. 75

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4

Gage pressure within a spherical droplet of a fluid is 'p'. What will be gage pressure within a bubble of the same size & of the same fluid?

A. p

B. 2 p

C. 0.5 p

D. 0.25 p

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4

Midrex process of sponge iron production uses reformed natural gas as the reducing agent, which uses iron ore in the form of

A. Lumps

B. Pellets

C. Briquettes

D. Sinter