The refrigerant freon-12 is chemically
CCl2F2
CCl3F
CClF3
CCl4F
Correct Answer :
A. CCl2F2
Related Questions
Spherical shape of mercury droplets is due to its
High viscosity
Low surface tension
High density
High surface tension
Non-ferrous alloys used for making cutting tools need not have high
Abrasion resistance
Toughness
Red hardness
Cutting speed
The transition temperature at which all the ferromagnetic materials become paramagnetic materials is termed as the 'Curie temperature'. Its value for cobalt is __________ °C.
768
1127
1359
1480
In a counter flow heat exchanger, hot fluid enters at 170°C & leaves at 150°C, while the cold fluid enters at 50°C & leaves at 70°C. The arithmetic mean temperature difference in this case is __________ °C.
20
60
120
∞
Adhesives
Cant be used in the form of pressure sensitive tapes
Cant join two dissimilar metals
Cure instantaneously after application on a surface
None of these
Probability of cavitation occuring becomes very high, when the local __________ resulting in water bubbles formation, which on rupture cause cavitation
Pressure falls below the vapour pressure
Pressure becomes very high
Temperature becomes low
All 'a', 'b' & 'c'
All the atoms of the world comprise of electrons, proton & neutron except that of __________ atom in which neutron is absent.
Deuterium
Hydrogen
Neon
Helium
Direct conversion of thermal energy to electrical energy is facilitated by the
Fuel cells
Photo voltaic cell
Magneto hydrodynamic generator
None of these
Ultimate strength in tension as compared to that in shear for steel is
Half
One third
One and half times
One fourth
The most economical channel section for the fluid flow is the one for which the discharge is maximum for a given cross-sectional area. Vertical velocity distribution in an open channel for laminar flow can be assumed to be
Parabolic
Hyperbolic
Straight line
None of these
Which of the following is not categorised as the ore agglomeration process?
Nodulising
Pelletising
Balling
Briquetting
Hot working of lead is carried out at
75°C
373°K
150°C
Room temperature
For a spontaneous natural process at constant temperature and pressure, the free energy of the system always
Increases
Decreases
Remain constant
Increases to a maximum before decreasing
Cobalt - 60 is used as a source of __________ in medical therapy & industrial radiography.
X-rays
γ-rays
α-rays
β-rays
Drills are usually made of
Cermets
High speed steel
Alloy steel
Tungsten carbide
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
During decarburising of a plain carbon steel, the thickness of ferrite layer growth is proportional to
Time
Square root of time
Square of time
Cube of time
The bolt is subjected to __________ when the nut is tightened by putting the washer beneath it.
Tension
Shear
Compression
Bending & tension
High relative humidity decreases the evaporative process and as the temperature is increased, the relative humidity decreases. The comfort range for human body is the ambient temperature of 22 to 27°C with relative humidity ranging from __________ percent.
5 to 10
15 to 25
45 to 50
75 to 80
Young's modulus of a material is the measure of its
Stiffness
Malleability
Creep resistance
Tensile strength
Pick out the wrong statement.
Copper is the metal having the highest electronic conductivity
Hardenability & Weldability of metals are inversely related
Covalent bonding formed by sharing of electrons is present in all semi-conductor materials
Glass transition temperature applies to 'polymers' but not to 'glasses'
Cemented carbide tools are not suitable for cutting
Aluminium
Brass
Cast iron
Steel
An ideal material for making cooking vessels should have
High heat capacity
Low heat capacity
High thermal conductivity
Both (B) and (C)
Steels with high carbon equivalent have poor Weldability, because in these steels during welding
Carbon and other alloying elements get oxidised from the weld pool
Excessive ferrite forms in the heat affected zone leading to poor toughness of the weld
Martensite forms in the heat affected zone leading to poor toughness/ductility of the weld
Segregation of carbon and other element occurs in the weld pool leading to poor properties of the weld
Vibration upto 100 kilo hertz can be most accurately measured by a __________ type accelerometer.
Preloaded spring
Piezoelectric
Bonded strain gauge
None of these
Atomic __________ of an element is a whole number.
Weight
Number
Volume
Radius
Which of the following processes follows the hardening process for reducing the hardening strains & increasing the toughness of the steel part?
Anodising
Tempering
Carburising
Annealing
Pick out the wrong statement.
Both annealing and normalising release the internal stresses of the material besides improving the mechanical properties
Low carbon steel does not respond to the heat treatment for hardening of the material, hence it is subjected to case hardening or surface hardening processes like cyaniding, carburising, nitriding etc., which produces high carbon outer layers resulting in increase of surface hardness
Induction hardening and flame hardening techniques are also used for surface hardening
Martempering of a material is a hardening process
Liquor poisoning generally occurs due to the presence of __________ in it.
Ethyl alcohol
Impurities
Methyl alcohol
Carbonic acid
Nitriding of a steel part does not increase its
Grain size
Fatigue limit
Surface hardness
Wear resistance