Which of the following materials does not form adherent oxide film on surface?
Copper
Nickel
Aluminium
Gold & silver
Correct Answer :
D. Gold & silver
Related Questions
According to thermodynamic Fahrenheit scale, the fundamental interval between ice point to steam point is
180°
212°
32°
273°
Pick out the wrong statement.
A soft magnetic material should have high permeability and small area of hysteresis loop
Poisson's ratio of high melting point metals is more than unity
Solders generally melt at less than 185°C
Steel produced by B.O.F process is ideally suited for manufacturing flat product
Silicon in steel
Makes it usable in almost all magnetic circuits where alternating current is used
Increases its electrical resistivity and decreases the hysteresis loss
Is present upto 5% & 4% respectively when used in transformers & motor armatures
All 'a', 'b' & 'c'
Filler material used in welding should have __________ as compared to the parent metal to be welded.
Lower melting temperature
Same melting temperature
Same composition
Both 'b' & 'c'
Tin based white metals are used, where bearings are subjected to
High pressure & load
Low pressure & load
High temperature
Large surface wear
The heat treatment to which the steel wire containing > 0.25% carbon is subjected to is
Full annealing
Bright annealing
Patenting
None of these
__________ has a negative co-efficient of linear expansion.
Iron
Copper
Rubber
Nickel
Dryness fraction of dry steam is
0
∞
1
0.5
Desalination of water
Makes it potable
Makes it non-potable
Means distillation of water
None of these
__________ test can be termed as the semidestructive test.
Impact
Torsion
Hardness
Charpy
For separating small pieces of metal from engine oil of a car, the best separating technique is the
Chromatography
Evaporation
Filtration
Fractional distillation
The underground well of a biogas plant is called the
Septic tank
Oxidation well
Digestor
Lagoon
Ferromagnetic materials owe their properties to __________ inner sub-shells.
Completely filled
Partially filled
Equally filled
Vacant
In __________ process, there is an increase in entropy with no degradation of energy.
Isothermal expansion
Isochoric heat addition
Polytropic expansion
Isobaric heat addition
Most of the phosphorous present in the blast furnace burden enters into
Hot metal
Flue gases
Slag
Refractory lining
Which of the following properties of a solid is not dependent on crystal imperfection?
Ductility
Semi-conductivity
Melting point
Yield stress
Lead is poured into the joint between two- __________ pipes.
Mild steel
Concrete
Cast iron
Asbestos cement
The ratio of mass of a neutron to that of an electron is about 1839. What is the ratio of the mass of a proton to that of an electron?
159
1837
2537
10000
Plastics as a material of construction suffer from the drawback of low
Machinability
Density
Strength
Plastic deformation
Which one can be directly solidified from gaseous state without entering into liquid state?
Helium
Oxygen
Carbon dioxide
None of these
The delivery pressure of boiler feed water pump compared to the boiler steam pressure is
Same
Slightly less
Slightly more
Much more
Brazing filler metal used for joining steel plates
Melts below the melting points of base metals
Melts below 300°C
Is copper phosphorous alloy
Is copper
Blast furnace slag is mainly molten
Sand
Magnesium silicate
Calcium silicate
Iron pyrite
For infinite parallel planes having emissivities ε1 & ε2, the interchange factor for radiation from surface 1 to surface 2 is given by
The minimum carbon content in steel should be __________ percent for it to respond to a hardening treatment.
0.2
0.4
0.6
0.8
With increasing carbon percent in steel beyond 0.8%, its ultimate tensile strength (UTS) and __________ is not affected.
Impact strength
Percent elongation
Hardness
Both 'b' & 'c'
As per the Indian boiler regulation (IBR), the type of joint preferred for the circumferential joint is the __________ joint.
Butt
Lap
Welded
None of these
Hot extrusion process is not used for making
Cast iron pipe for domestic water supply
Aluminium curtain rods
Stainless steel tubes used in furnitures
Any of these
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
The best guide to judge the general quality of water is the measurement of its
pH value
Electrical conductivity
Turbidity
Dissolved oxygen content