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4

Minimum thermal efficiency of a steam boiler may be around __________ percent

A. 25

B. 45

C. 65

D. 20

Correct Answer :

D. 20


Related Questions

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Which of the following is not a principal alloying element for the structural steel?

A. Molybdenum

B. Nickel

C. Manganese

D. Chromium

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4

Induced draft fans provided in large thermal power plant boilers have __________ blades.

A. Forward curved

B. Backward curved

C. Double curved

D. Radial or straight

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4

Metal cutting by oxy-acetylene flame is accomplished by the __________ of the metal.

A. Burning

B. Intensive oxidation

C. Evaporation

D. None of these

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4

Pick out the wrong statement.

A. The X-rays cannot be deflected by electric field unlike cathode rays

B. The intensity of X-rays can be measured by ionisation current produced due to the ionisation of gas by X-rays

C. The quality of X-rays can be controlled by varying the anode-cathode voltage

D. Crystal structure of a material can be studied by an electron microscope

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__________ remains constant during the adiabatic cooling of moist air.

A. Wet bulb temperature

B. Dry bulb temperature

C. Relative humidity

D. Specific humidity

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4

Which of the following is not an explosive?

A. TNT

B. CMC

C. RDX

D. Lead azide

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4

A compact estimate about the amount of materials handling between various work stations is obtained from the

A. Gantt chart

B. Bin chart

C. String diagram

D. Travel chart

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4

Highest cutting speed is achieved by the __________ tool material.

A. High speed steel

B. Carbide

C. Cast alloy

D. Plain carbon steel

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4

Basic open hearth furnace (BOF) is not used for producing __________ steel.

A. Killed

B. Rimming

C. High alloy

D. None of these

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4

Pick out the wrong statement.

A. Copper is the metal having the highest electronic conductivity

B. Hardenability & Weldability of metals are inversely related

C. Covalent bonding formed by sharing of electrons is present in all semi-conductor materials

D. Glass transition temperature applies to 'polymers' but not to 'glasses'

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4

Baffles provided on the shell side of a shell and tube heat exchanger are meant for

A. Providing support for the tubes

B. Improving heat transfer

C. Both 'a' & 'b'

D. Preventing the fouling of tubes & stagnation of shell side fluid

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4

A semi-conductor is damaged & behaves like a conductor, on passing a strong electric current through it, because it heats up the crystals & breaks the covalent bonds resulting in __________ electrons.

A. Lack of free

B. Excess of

C. Decrease in

D. None of these

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4

According to maximum shear stress failure criterion, yielding in material occurs, when the maximum shear stress is equal to __________ times the yield stress.

A. 0.5

B. 2

C. √2

D. √3/2

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4

What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively.

A. 2

B. 8

C. 10

D. 40

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4

Fog is an example of colloidal system of

A. Solid dispersed in gas

B. Solid dispersed in liquid

C. Liquid dispersed in gas

D. Gas dispersed in liquid

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4

Which of the following fastening devices has a head at one end and a nut fitted to the other?

A. Bolt

B. Stud

C. Top bolt

D. None of these

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4

Lead pencil contains

A. Graphite

B. Lead sulphide

C. Lead

D. Both (B) & (C)

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4

In the X-ray radiography technique, the tube voltage for thicker plates as compared to thin plates, should be

A. Higher, as it gives higher wavelength

B. Lower, as it gives higher wavelength

C. Higher, as it gives shorter wavelength

D. Lower, as it gives shorter wavelength

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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

Large diameter reinforced cement concrete (RCC) pipes are generally joined by __________ joint.

A. Flanged iron

B. Collar

C. Flexible

D. Expansion

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4

During sensible cooling of air, its wet bulb temperature

A. Decreases but dew point remains constant

B. Increases but dew point remains constant

C. Increases & the dew point decreases

D. Decreases & the dew point increases

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4

Which of the following is not used as a bearing material?

A. Copper-lead alloys

B. Babbitts

C. Bronzes

D. Cermets

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4

With increase in annealing temperature, the following defect density decreases.

A. Vacancy

B. Dislocation

C. Grain boundary

D. All of these

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4

The refractory brick which has good thermal shock resistance at high temperature but cracks on cooling below 400°C is

A. Magnesite

B. Chrome

C. Silica

D. Fireclay

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4

__________ is not a case hardening process.

A. Carburising

B. Nitriding

C. Cyaniding

D. Annealing

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4

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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4

Dies for wire drawing are generally made of

A. Mild steel

B. Stainless steel

C. Carbides

D. High carbon steel

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4

Out of the following, the best material capable of withstanding shock & vibration without the danger of cracking is

A. Malleable iron

B. Grey cast iron

C. Chilled cast iron

D. White cast iron

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A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre.

A. 0.01

B. 0.1

C. 0.25

D. 0.5

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4

The only suitable method for hardening the low carbon steel is case hardening. Which of the following is a case hardening process?

A. Cyaniding

B. Sherardizing

C. Spheroidising

D. None of these