Matte smelting is used in the extraction of
Lead
Zinc
Aluminium
Copper
Correct Answer :
D. Copper
Related Questions
Work required for compression of a gas contained in a cylinder is 7000 kJ. During compression, heat interaction of 3000 kJ causes the surroundings to be heated. Internal energy change of the gas during the compression is __________ kJ.
+4000
-4000
10000
-10000
The same volume of all gases is representative of their
Specific gravities
Densities
Gas characteristic constants
Molecular weights
Which of the following is the most suitable material of construction for the condenser tubes, where the cooling medium is brine (salty water)?
Aluminium
Copper
Titanium
Stainless steel
M10 index of coke indicates its
Compressive strength
Hardness
Abrasion resistance
Impact strength
Primary designation of steel is based on its
Hardness & tensile strength
Carbon content
Iron content
Alloying elements content
Maximum change in the hardness of martensite occurs in the carbon content range of __________ percent in steel.
0.01 to 0.10
0.2 to 0.4
0.5 to 0.7
0.8 to 1.0
Use of economiser in a boiler plant reduces the fuel consumption for steam generation by about __________ percent.
1
10
30
50
An ideal material for making cooking vessels should have
High heat capacity
Low heat capacity
High thermal conductivity
Both (B) and (C)
With increase in __________ Knocking tendency in a spark ignition petrol engine decreases.
Supercharging
Wall temperature
Compression ratio
Engine speed
Identify the false statement
Martensitic steels are less susceptible to pitting corrosion than austenitic steels
Pitting corrosion is usually very localised
Hydrogen embrittlement is facilitated by tensile stress
Stress corrosion cracking is facilitated by tensile stress
The minimum temperature to which the water can be cooled in a cooling tower is the __________ temperature of air.
Ambient
Dry bulb
Dew point
Wet bulb
__________ are normally subjected to sub-zero treatment.
Highly stressed parts
Gauges or precision parts
Cold rolled sheets
Non machinable materials
Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting)
V/A
V/A2
V2/A
V2/A2
Which one can be directly solidified from gaseous state without entering into liquid state?
Helium
Oxygen
Carbon dioxide
None of these
Percentage of argon (by volume) in dry atmospheric air is about
0.09
0.3
0.57
0.94
The kinematic viscosity (in stoke) and the absolute/dynamic viscosity (in poise) are the same for __________ at room temperature.
Air
Water
Mercury
Alcohol
Lead is poured into the joint between two __________ pipes.
Mild steel
Concrete
Cast iron
Asbestos cement
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
Increase in the entropy of a system represents the
Degradation of energy
Decrease in system pressure
Increase in the availability of energy
Increase in the temperature
Brazing is the joining of metals
Without melting the base metal
With a non-ferrous filler
Both (A) & (B)
Neither (A) nor (B)
Normalising does not __________ of a metal.
Improve machinability & tensile strength
Remove internal stresses
Refine the structure
Remove strains caused by cold working
Gross national product (GNP) means the total value of __________ in a country.
Goods produced
Gold reserve
Earning of the citizens
Taxes paid
Thermodynamic cycle involved in the working of a thermal power plant is the __________ cycle.
Joule
Carnot
Rankine
Brayton
Pick out the wrong statement about nucleate boiling.
Bubble generation is by expansion of entrapped gas/vapour at small cavities in the surface
Surface temperature is greater than the saturation temperature of the liquid
Heat transfer from the surface of the liquid is less than that in film boiling
The temperature is less than that of film boiling
Fire refining process is employed in case of
Tin
Copper
Zinc
Aluminium
__________ is the process of coating the surface of steel with aluminium oxide, thereby imparting it increased resistance to corrosion & oxidation upto a temperature of 700°C.
Veneering
Galvanising
Electroplating
Calorising
Which of the following is not a characteristic observed in material failure by fatigue fracture?
Plastic deformation of material does not occur
Initiation of crack from below the surface does not occur
Initiation of crack occurs on the surface of the machine part
Presence of both rough & smooth zone with conchoidal markings in smooth zone of the surface
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
Normalising of an object does not
Refine coarse grain structure obtained during hot working
Improve ductility
Improve yield strength
Improve mechanical properties
__________ is the process used for setting up compressive stresses in the surface of a metal to improve its fatigue strength.
Lancing
Shot peening
Slugging
Spinning