With increase in impurities in metals, their corrosion resistances
Increase
Decrease
Remain same
May increase or decrease; depending on the type of metal
Correct Answer :
B. Decrease
Related Questions
Which of the following test is used for distinguishing among dry oils, semi-drying oils and non drying oils?
Elaiden test
Reichert-Meissl value test
Hunter value test
Iodine value test
A solar cell converts the sunlight directly into __________ energy.
Thermal
Electrical
Mechanical
Chemical
A solution which resists change in its pH value on addition of acid/alkali is called the __________ solution.
Neutral
Ideal
Buffer
Zero pH
Gantt charts are used for streamlining the
Inventory control
Production schedule
Sales forecasting
Quality control
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
Which one can be directly solidified from gaseous state without entering into liquid state?
Helium
Oxygen
Carbon dioxide
None of these
The thermodynamic law, 
= constant, is not followed by the
Free expansion of an ideal gas
Adiabatic expansion of steam in turbine
Adiabatic compression of air
Ideal compression of air
The value of 
for air & most common gases can be safely assumed to be
0.8
1
1.4
1.8
Drills are usually made of
Cermets
High speed steel
Alloy steel
Tungsten carbide
Out of the following __________ iron has the best capability to bear sudden & excessive shocks.
White
Cast
Wrought
Pig
__________ is not a case hardening process.
Carburising
Nitriding
Cyaniding
Annealing
Which of the following is the most suitable abrasive for grinding high tensile strength materials?
Silicon carbide
Corundum
Aluminium oxide
Boron carbide
Increase in temperature, in general results in the
Decrease in the viscosities of both liquids & gases
Increase in the viscosities of both liquids & gases
Increase in the viscosity of liquids and decrease in that of gases
Decrease in the viscosity of liquids and increase in that of gases
At 100% relative humidity, the dew point temperature of moist air is
Less than the wet bulb temperature
More than the wet bulb temperature
Equal to the wet bulb temperature
Equal to the ambient temperature
The noble metals
Are exemplified by Na, K and Li
Do not resist corrosion very strongly
Are the lowermost in the electro-chemical series of metals
None of these
__________ is the hardest oxide and is hence used where high wear resistance at high temperature is required.
Beryllium
Zirconia
Alumina
Magnesia
Out of the following, the most malleable material is
Copper
Aluminium
Wrought iron
Lead
Main constituent of bone ash is
Ammonium phosphate
Calcium phosphate
Animal charcoal
Ammonium sulphate
__________ is the most important element, which controls the physical properties of steel.
Manganese
Silicon
Carbon
Vanadium
Cold heading or upsetting is categorised as the __________ process.
Extrusion
Bending
Rolling
Forging
Which of the following has the highest value of refractive index?
Brine (sea water)
Diamond
Distilled water
Glass
Catalyst used in the catalytic converter employed in automobiles to convert CO into CO2 and for complete oxidation of un-burnt hydrocarbons is
Nickel
Cobalt
Vanadium
Platinum
Softening of hardened steel is done by its
Normalising
Tempering
Annealing
Carburising
Breakeven point represents the condition, when the company runs under no profit no loss condition. In break even analysis, total cost comprises of fixed cost
Only
Plus variable cost
Plus overhead cost
Plus selling expenses
Minimum safe distance between two liquid fuel storage tanks is equal to (where, H = height of the tank)
H
H/2
H/4
H/6
Which of the following materials has the poorest electrical conductivity?
Carbon
Aluminium
Silver
Stainless steel
Super conduction in metals is observed at a temperature of __________ °K.
<100
>100
About 273
About 373
Work hardenable alloy steel used to make the bucket wheel excavators, blades of bulldozers and other earth moving equipments contain iron, carbon and
Manganese
Silicon
Nickel
Chromium
In an eutectic system, two elements are completely
Soluble in solid state
Insoluble in liquid state
Insoluble in both solid & liquid state
Soluble in liquid state
Friction factor for fluid flow in pipe does not depend upon the
Pipe length
Pipe roughness
Fluid density & viscosity
Mass flow rate of fluid