__________ rubber is generally used for making 'O' rings used for vacuum sealings.
Natural
Neoprene
Butadiene
Nitrile
Correct Answer :
B. Neoprene
Related Questions
The temperature at which the magnetic property of iron disappears (i.e., it becomes non-magnetic) and its electrical conductivity & specific heat also changes, is called the 'Curie point', which is __________ °C.
768
908
1400
1539
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 difference in one unit of Rockwell hardness number corresponds to a difference in the depth of indentation of __________ mm.
0.001
0.01
0.002
0.02
Desalination of water
Makes it potable
Makes it non-potable
Means distillation of water
None of these
Preheating before welding is done to
Make the plate softer
Burn oil & grease sticking to plate surfaces
Avoid plate distortion
Prevent cold cracks
Angular displacement can be measured suitably by a
Shaft encoder
Linear variable differential transducer (LVDT)
Stroboscope
Tachometer
Which of the following are considered applications of ultrasonic testing?
Determination of elastic constant
Detection of defects in metal
Measurement of material thickness
None of the above
Principal alloying element in Elinvar (used for making hair springs for watches) is
Copper
Aluminium
Nickel
Zinc
Steel & cast iron pipes are produced by __________ casting.
Slush
Die
Investment
True centrifugal
The best guide to judge the general quality of water is the measurement of its
pH value
Electrical conductivity
Turbidity
Dissolved oxygen content
Other parameters remaining same, the recrystallisation temperature of an alloy is lowered, when
Strain rate is increased
Grain size is increased
Prior cold deformation is increased
Not affected by any of the above parameters
High endurance limit of carburised machine parts is because of the fact that carburisation
Suppresses any stress concentration produced in the parts
Enhances the yield point of the material
Introduces a compressive layer on the surface
Produces a better surface finish
Plasma is
A high temperature neutral gas
Nothing but ionised gas
A source of steady and highest controllable pressure
Formed at very low temperature
The size of the tetrahedral void in the closest packing of atoms is __________ that of the octahedral void.
Equal to
Greater than
Less than
Either (A), (B) or (C); depends on the size of atom
The difference between gross & net calorific values of fuel is due to the
Sensible heat carried away by the flue gases
Heat carried away by the steam from the moisture content of the fuel
Heat lost by radiation
Heat carried away by steam from the combustion of hydrogen in the fuel
Fire in fuel gas pipelines is extinguished most effectively by
Spraying water
Blanketting the area with nitrogen atmosphere
Fire fighting foam
None of these
Alcohols are not suitable as diesel engine fuel because the cetane number of alcohols is
Very low which prevents their ignition by compression
Very high which prevents their ignition by compression
Zero
None of these
With increase in temperature, the electrical conductivity of a __________ decreases.
Semi-conductor
Metal or alloy
Dielectric
None of these
Enzymes belong to the category of
Proteins
Carbohydrates
Vitamins
Fats
Large scale fire on fuel gas line is normally extinguished by
Water
Steam
Foam
Nitrogen
Cold chisel & hammers are made of
High speed steel
High carbon steel
Forged steel
Mild steel
Auto collimator is used to check
Flatness
Angle
Rotor balancing
Roughness
Normalising of an object does not
Refine coarse grain structure obtained during hot working
Improve ductility
Improve yield strength
Improve mechanical properties
Alloying elements present in Haynes stellite, which has superior performance than high speed steel, are:
Nickel, cobalt & chromium
Tungsten, chromium & cobalt
Manganese, chromium & cobalt
Tungsten, molybdenum & nickel
The usual energy consumption in electric arc furnace steel making is __________ KWh/ton of steel.
60 - 100
400 - 700
1200 -1500
2000 - 2300
Larger length & diameter water pipes are made by
Electrical resistance welding
Die casting
Semi-centrifugal casting
Continuous casting
Property responsible for the talcum powder to cling to the skin is the
Capillary action
Adhesion
Cohesion
Surface tension
Which of the following is not a charge material for cupola?
Limestone
Iron scrap
Iron ore
Pig iron
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
Capacity & power requirement for an air compressor working at high altitude compared to sealevel will be
More
Less
Same
Either more or less; depends on the climatic conditions