The refractory lining of the bottom in a basic electric arc furnace is made of
Silica
Alumina
Magnesia
Fireclay
Correct Answer :
C. Magnesia
Related Questions
Which of the following metals is not subjected to electrolytic refining/purification?
Copper
Zinc
Tin
Aluminium
Vibration upto 100 kilo hertz can be most accurately measured by a __________ type accelerometer.
Preloaded spring
Piezoelectric
Bonded strain gauge
None of these
Which of the following emissions in the exhaust gas of an I.C. engine causes the formation of photochemical smog?
Nitrogen oxides
Hydrocarbons
Both 'a' & 'b'
Carbon monoxide
Pick out the wrong statement about coating/electroplating of metals.
Phosphate coating is used as an excellent base for paints & enamels
Phosphate coating is less corrosion resistant than chromate coating
The base metal to be electroplated is normally made the cathode of the electrolytic cell and coating metal is made the anode
Calorising is the process of coating steel with chromium
Common salt is produced from sea water in India generally by the __________ method.
Freeze drying
Solar evaporation
Electrolytic
None of these
The excess air required for the combustion of pulverised coal is of the order of about __________ percent.
5
15
30
45
The bank of tubes located at the back of the domestic refrigerators are the __________ tubes.
Refrigerant cooling
Evaporator
Condenser
Throttling
Other parameters remaining same, the recrystallisation temperature of an alloy is lowered, when
Strain rate is increased
Grain size is increased
Prior cold deformation is increased
Not affected by any of the above parameters
Atomic __________ is a whole number for an element.
Number
Weight
Radius
None of these
What happens, when SO2 is passed through a solution of H2S in water?
Precipitation of sulphur takes place
H2SO3 is formed
Oleum is formed
None of these
The elastic strain energy of a unit length of an edge dislocation as compared to that of a screw dislocation is
More
Equal
Less
Double
The stress at which extension of the material takes place more rapidly as compared to the increase in load is termed as the __________ point of the material.
Elastic
Ultimate
Yielding
Breaking
Air/fuel ratio by weight for combustion of methane with theoretical quantity of air will be about
9 : 1
17 : 1
23 : 1
29 : 1
__________ flux is used for the extraction of metal from its self fluxing ores.
No
Acid
Basic
Neutral
Alcohols are not suitable as diesel engine fuel because the cetane number of alcohols is
Very low which prevents their ignition by compression
Very high which prevents their ignition by compression
Zero
None of these
On oscilloscope screen for dynamic measurement, lissajous diagram is normally used to determine the __________ of the input signal.
Frequency
Amplitude
Damping
None of these
Regeneration of molecular sieve requires it to be heated to a temperature of about __________ °C.
80-120
200-300
600-800
1000-1100
Pick out the correct statement
Jet engine can work, where there is no atmosphere
Rocket engines cannot work, where there is no atmosphere
Rocket engines carry oxygen required for the combustion in the form of oxidiser
Jet engines also carry oxidiser
Optical activity is a/an __________ property.
Additive
Constitutive
Both (A) & (B)
Neither (A) nor (B)
Production of a hollow product by inflation of a tube or parison is called the __________ process.
Blow moulding
Calendaring
Extrusion
Injection
What is the percentage of chromium in 18-4-1 high speed steel?
1
4
18
23
The usual energy consumption in electric arc furnace steel making is __________ KWh/ton of steel.
60 - 100
400 - 700
1200 -1500
2000 - 2300
The dew point of moist air becomes __________ with decrease in its relative humidity.
Less than the wet bulb temperature
More than the wet bulb temperature
More than the dry bulb temperature
Equal to wet bulb temperature
Circular cross section machine parts which are symmetrical about the axis of rotation are made by hot
Piercing
Spinning
Drawing
Extrusion
Water hammer is caused in steam carrying pipelines, because of
Partial condensation of steam
Vibration of the pipeline
High degree of superheat of steam
Its exposure to torrential rain
In the blast furnace, incorporation of water vapour in the blast gives the following effect.
Increases the reducing potential of the gas
Increases the flame temperature
No significant change occurs
Increases the hydrogen content in the metal
Heating of ferromagnetic materials to a temperature above Curie temperature makes it
Insulator for heat & electricity transmission
Ferritic
Behave like paramagnetic materials
Superconductor
Removal of non-condensable from steam or other vapour is termed as the __________ process.
Condensation
Deaeration
Scavenging
Exhaust
Enzymes belong to the category of
Proteins
Carbohydrates
Vitamins
Fats
Boiler tube size is specified by its thickness and __________ diameter.
Outside
Inside
Mean
None of these