Regeneration of molecular sieve requires it to be heated to a temperature of about __________ °C.
80-120
200-300
600-800
1000-1100
Correct Answer :
D. 1000-1100
Related Questions
The rolling process cannot be used to produce
Plates
Rods
Tubes
Wires
Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)
1/k
k
k2
1/k2
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.
150
200
300
400
Which of the following materials does not form adherent oxide film on surface?
Copper
Nickel
Aluminium
Gold & silver
The laminar boundary layer thickness in zero pressure gradient flow over a flat plate along the x-direction varies as x0.5 while the thickness of turbulent boundary layer varies as (where, x = distance from the leading edge)
x1.5
x0.8
x-1.5
x-0.8
Annealing of cast iron
Softens it to facilitate machining
Decreases the free carbon
Increases the strength
None of these
Which of the following has the least value of ultimate tensile strength (UTS)?
Medium carbon steel
High carbon steel
Cast iron
Wrought iron
Which of the following relationships is correct for relating the three elastic constants of an isotropic elastic material (where, E = Young's modulus, G = Modulus of rigidity or shear modulus v = Poisson's ratio)?
E = 2G (1 + v)
E = G (1 + v)
E = G (1 + v)/2
E = 2G (1 + 2v)
Between 230 and 370°C, blue brittleness is caused in mild steel because of the
Immobility of dislocation
Strain-ageing
Increase in Young's modulus
Strain hardening
Pick out the wrong statement.
Seam welding, projection welding & spot welding are the classification of electrical resistance welding
Electrode tip in spot welding is of copper and the tip diameter should be equal to t (where, t = plate thickness to be welded)
In spot welding, two pieces to be joined are overlapped and placed between two electrodes
Mild steel sheet cannot be spot welded
Which of the following materials has the poorest electrical conductivity?
Carbon
Aluminium
Silver
Stainless steel
An example of unsteady non uniform flow is the flow of liquid under pressure through a
Tapering pipe at constant flow rate
Tapering pipe at either decreasing or increasing flow rate
Long pipeline of constant diameter
None of these
Pick out the correct statement.
Hot worked materials are subjected to annealing to remove internal stresses
Annealing of steel hardens it slightly
Normalising of a material induces stresses
Tempering of a material improves ductility & toughness but reduces hardness & brittleness
On oscilloscope screen for dynamic measurement, lissajous diagram is normally used to determine the __________ of the input signal.
Frequency
Amplitude
Damping
None of these
Oxide layer formed on the non-ferrous metal surface after its annealing is
Removed by acid pickling
Hammered into the surface
Removed with coarse emery cloth
Left as such to protect the surface
Addition of __________ to steel does not help in improving its machinability.
Sulphur
Silicon
Lead
Phosphorous
Which of the following materials has the maximum shrinkage allowance?
Brass
Cast iron
Lead
Aluminium alloy
Which of the following performance characteristics of a S.I engine is not affected by the front end volatility of the petrol used?
Vapour locking
Hot starting
Spark plug fouling
All 'a', 'b' & 'c'
The swift cup test evaluates the following property of a sheet metal.
Stretchability
Drawability
Bendability
None of these
Lead is poured into the joints between two __________ pipes.
Cast iron
Steel
Concrete
Plastic
For the irreversible reaction, Ca+ 2C = Ca C2 , Δ H°298 = - 60000 J . mole-1 . If a system initially containing 2 moles of calcium, 3 moles of carbon and 1 mole of calcium carbide is allowed to react to completion, the heat evolved at 298 K will be
30,000 J
60,000 J
90,000 J
2,40,000 J
Heat required to raise the temperature of a body by 1 °C is called its
Heat capacity
Specific heat capacity
Thermal conductivity
Water equivalent
Lead pencil contains
Graphite
Lead sulphide
Lead
Both (B) & (C)
Nickel and __________ are the alloying element added in steel to increase its toughness.
Molybdenum
Chromium
Vanadium
Silicon
Silicon crystal can be converted to p-type semiconductor by doping with
Phosphorous
Nitrogen
Carbon
Boron
Materials having __________ lattice structure are usually the most ductile.
Body centred cubic (bcc)
Hexagonal close packed (hcp)
Face centred cubic (fcc)
None of these
Fibre glass is a composite material of
Glass fibre in a polymer matrix
Glass fibre in a metallic matrix
Polymer fibre in a glassy matrix
Both 'b' & 'c'
The critical pressure at which the latent heat of vaporisation of steam becomes zero is __________ Kg/cm2.
273.15
225.65
100.03
373.15
Circular cross section machine parts which are symmetrical about the axis of rotation are made by hot
Piercing
Spinning
Drawing
Extrusion
The pressure outside a bubble/droplet of liquid is __________ the internal pressure.
Greater than
Less than
Equal to
Unpredictable; depends on the bubble size