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
Correct Answer :
A. Removed by acid pickling
Related Questions
Which of the, following is not associated with the functioning of a petrol engine?
Compression ignition system
Spark plug
Carburettor
Otto cycle
Electrostatic separation of minerals from each other is based on their differences in the following property.
Densities
Magnetic permeabilities
Electrical conductivities
Hardness
Pick out the correct combination about the role of various additives used in polymers.
Plasticiser: increases the polymer strength
Heat stabiliser: increases the maximum service temperature
Fillers: Does not affect the property of polymer but increases its weight
Lubricants: increases the flexibility of polymers
Carbide tipped cutting tools are manufactured by powder metallurgy techniques and have a composition of
90% tungsten carbide and 10% cobalt
70% aluminium oxide & 30% silica
30% nickel, 15% chromium & 55% tungsten
65% tungsten & 35% zirconium
The substance used as a smoke screen in warfare is
C2H2
SiCl4
P2O5
PCl5
Annealing of white cast iron produces __________ iron.
Grey
Nodular
Malleable
Spheroidal
The ratio of thermal & electrical conductivity is same for all the metals at the same temperature; and at around room temperature, this ratio is proportional to(where, T = absolute temperature, °K)
T
1/T
T2
1/T2
Brass parts with high residual tensile stress at the surface are susceptible to season cracking (i.e. spontaneous cracking occuring on exposure to atmospheric corrosion), if its zinc percentage is more than
5
10
20
35
Temperature of hot gases flowing in a pipe is measured by a thermocouple inserted in the thermal well. The thermal well made of __________ will facilitate the most accurate measurement of the temperature.
Copper
Steel
Aluminium
Brass
__________ is the hardest material out of the following.
Boron carbide
Tungsten carbide
Hardened steel
Silicon carbide
Constituents of stellite are
Zinc, copper & nickel
Cobalt, chromium & tungsten
Zinc, aluminium & nickel
Nickel, cobalt & vanadium
Out of the following substances, one ton of __________ will store the maximum heat for a rise of 30°C in temperature.
Steel
Lignite
Water
Lime stone
Dew point temperature always gives an indication of the __________ of the moist air.
Dryness
Moisture content
Coolness
Latent heat
A material being tested for endurance strength is subjected to the __________ load.
Impact
Completely reversed
Dynamic
Static & dynamic
Stresses encountered in the metal forming processes are less than the __________ of the material.
Fracture strength
Yield strength
Elastic limit
Limit of proportionality
Elimination of brittleness resulting from welding of saw blades is done by __________ of the welded portion.
Annealing
Toughening
Work hardening
Tempering
In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is
1
1.4
1.5
Y = Cp/Cv
__________ the exhaust gas is an indication of the incomplete combustion of fuel.
Low temperature of
High temperature of
High % of CO in
High % of CO2 in
The ratio of the shear stress to the principal stress on a principal plane is
0
1
1/2
1/3
Which of the following is not the commercial name of poly-methyl-methacrylate (PMMA)?
Styrofoam
Lucite
Perspex
Plexiglass
Pick out the wrong statement.
Complete unity of command exists in a line organisation
Line organisation is net suitable for expansion and growth of an industry
In line and staff organisation, line executes and staff directs
None of these
Current employed in resistance welding ranges from __________ kVA/
.
1.2 to 2.5
4.5 to 6.2
7.5 to 8.5
10.5 to 15.5
Direct conversion of thermal energy to electrical energy is facilitated by the
Fuel cells
Photo voltaic cell
Magneto hydrodynamic generator
None of these
Blast furnace slag is mainly molten
Sand
Magnesium silicate
Calcium silicate
Iron pyrite
Powder metallurgy is used to produce
High precision components with complex cavities and sharp features
Components of large size
Porosity free components
Components of such alloys whose constituents do not form alloys readily
Which of the following metals cannot be hot worked at room temperature?
Zinc
Nickel
Lead
Tin
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
With increase in __________ Knocking tendency in a spark ignition petrol engine decreases.
Supercharging
Wall temperature
Compression ratio
Engine speed
A fluid is termed as the Newtonian fluid, when the shear stress is __________ the velocity gradient.
Independent of
Inversely proportional to
Directly proportional to
None of these
Hydro-cyclone is a
Crusher
wet classifier
Dry classifier
Magnetic separator