Hardening of steel is not possible, unless it is heated __________ critical point.
Above the highest
Above the lowest
Between the first & second
Between the second & third
Correct Answer :
B. Above the lowest
Related Questions
Pick out the correct statement about the condensation.
Filmwise condensation gives a lower heat transfer rate than the dropwise condensation
Suitable coating or vapour additive is used to promote film wise condensation
If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it
Reynolds number of condensing liquid is based on its mass flow rate
The underground well of a biogas plant is called the
Septic tank
Oxidation well
Digestor
Lagoon
As per international norms, the maximum permissible value of noise level in the industrial environment is __________ decibels as measured at a distance of 1.5 metres from the source of noise.
110
85
60
45
Basicity 
of the slag in Indian blast furnace is in the range of
0.7-1.0
1.1-1.4
1.5 - 1.8
2.0 - 2.5
Metalloids
Are good conductor of heat & electricity
Act as electron donors with metals & as electron acceptor with non-metals
Are not necessarily solids at room temperature
Are compounds that exhibit both metallic & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
With decrease in the grain size of a material, its creep resistance
Increases
Decreases
Remain constant
Either (A) or (B); depends on the material
Air intake for an air compressor should be preferably taken from
A site, where cooling towers are located nearby
A site, where open coal yard in located nearby
An air conditioned room maintained at a temperature of 18°C
An outside atmosphere at 10°C
The maximum stress below which a material can withstand an infinite number of cycle of stress, is termed as the
Fatigue strength
Creep strength
Resilience
Endurance limit
Hot dipping process is used for coating a low melting point metal (e.g. Pb, Sn, Zn) on iron, steel & copper having relatively higher melting points. Which of the following is not a hot dipping process?
Galvanising
Tinning
Sherardizing
None of these
Half life of a radioactive isotope corresponds to the time required for half of the __________ to decay.
Atoms
Neutrons
Nucleons
Electrons
Minimum number of members required to form a Public Limited Joint Stock Com-pany is
7
10
12
17
Solute atoms which cause yield point phenomenon in mild steel are/is
Aluminium
Boron
Carbon
Nitrogen
Inertial forces are obtained, when the elastic forces are multiplied by __________ number.
Mach
Froude
Reynolds
Euler
Ferromagnetic materials owe their properties to __________ inner sub-shells.
Completely filled
Partially filled
Equally filled
Vacant
Heat transfer by __________ is almost absent in case of fluidised bed drying operation.
Radiation
Conduction
Convection
Both (B) & (C)
L.D. (Linz-Donawitz) converter is used in the production of
Copper
Steel
Zinc
Aluminium
The most suitable material for die casting is
Iron
Copper
Steel
Nickel
Which of the following material handling equipments is not suitable for moving materials in varying paths?
Hand trolley
Belt conveyor
Crane
Truck
Basic open hearth furnace (BOF) is not used for producing __________ steel.
Killed
Rimming
High alloy
None of these
Though tin occurs lower than iron in the electrochemical series, yet it is coated on steel for corrosion protection, because of its
Lower cost
Abundant availability
Resistance to vegetable acids as the tin plate are commercially used in 'canning' industry
None of these
Fire in fuel gas pipelines is extinguished most effectively by
Spraying water
Blanketting the area with nitrogen atmosphere
Fire fighting foam
None of these
Coating thickness in case of galvanising of steel sheet generally corresponds to the deposition of __________ gms of zinc per 
of steel strip.
5-10
1000-1500
120-500
1500-3000
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
Shaft/rotor speed is most accurately measured by a
Frequency counter
Tachometer
Strobometer
Speedometer
Gas turbine normally employs a constant __________ cycle.
Pressure
Temperature
Volume
None of these
Which of the following is a boiler accessory
i.e., not a boiler mounting?
Blow off cock
Feed check valve
Feed water pump
Stop valve
In the Bayer's process, bauxite is digested under pressure using
H2SO4
NaOH
NH3
HCl
Cold heading or upsetting is categorised as the __________ process.
Extrusion
Bending
Rolling
Forging
__________ pipe is the most suitable for carrying sanitary drainage.
Stainless steel
Reinforced cement concrete
Cast iron
Asbestos cement
The substance used as a smoke screen in warfare is
C2H2
SiCl4
P2O5
PCl5