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
Correct Answer :
D. Are compounds that exhibit both metallic & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
Related Questions
Spark plug is provided in a/an
Engine having carburettor
Diesel engine
Compression ignition engine
Both (B) & (C)
The two elements required to form substitutional solid solution should not have
Same crystalline structure
Same valency
Widely differing electronegativity
Same atomic sizes
The specific gravity of coal depends mainly on its __________ content.
Carbon
Volatile matter
Ash
Moisture
In practice, the compression ratio of compression-ignition (CI) engine ranges from
15 to 25
5 to 10
40 to 55
60 to 70
Leakage in a cooking gas cylinder is detected by
Radio-isotopes
Pouring soap solution on the surface and locating the gas bubbles
Halide torch
Pungent smell of mercaptans present in the gas
Batch process is preferred over continuous process, when the
Product yields and quality cannot be achieved in continuous process, because of long residence time
Sales demand of product is not steady
Same equipment cannot be used for several processes of the same nature
All (A), (B) & (C)
Case hardening is not done by
Nitriding
Hot dipping
Electroplating
Both b & c
Out of the following the refractive index is the highest for
Glass
Diamond
Brine
Kerosene
In case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is
More
Less
Equal
Much more
Rain drops falling through atmospheric air attain limited terminal velocity, because of
Upward thrust due to air
Viscous force exerted by air
Surface tension effects of water
Force of gravity
Hot working of lead is carried out at
75°C
373°K
150°C
Room temperature
The most important requirement for aluminium industry is the availability of cheap
Ore
Electrical power
Labour
Abundant water
Force between the molecules of the same substance is called __________ force.
Adhesive
Cohesive
Molecular
Vander Walls
The taper provided on pattern for its easy & clean withdrawal from the mould is termed as the __________ allowance.
Casting
Pattern
Draft
Distortion
Neutrons are present in all atoms except that of
He
C
H
Ar
__________ of test specimens is not involved in any hardness testing method.
Fracture
Indentation
Wear
Scratch
In case of brasses, with decreasing zinc percentage and increasing copper percentage, its __________ increases.
Percentage elongation
Brinell hardness
Tensile strength
All 'a', 'b' & 'c'
Identify the correct statement with reference to the extractive metallurgy of aluminium.
The electrolyte consists of molten Na3AlF6 with approximately 1 to 8% Al2O3
Approximately 80% of the aluminium deposited on the cathode comes from cryolite
Sodium is deposited along with aluminium, but is immediately vaporised
Anode effect sets in when the cryolite concentration goes below 40%.
A jig is used while __________ a hole.
Boring
Counter boring
Drilling
Enlarging
Window panes of aeroplanes are normally made of
Perspex (PMMA)
Teflon (PTFE)
Bakelite (phenol formaldehyde)
Polystyrene
Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type
Parallel flow with equal heat capacities
Counter flow with equal heat capacities
Counter flow with unequal heat capacities
Parallel flow with unequal heat capacities
__________ 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
Corrosion rate cannot be lowered by reducing the __________ of the corroding medium.
Concentration
Velocity
Temperature
None of these
Square steel key is normally strong in failure by shear & crushing. Keys are normally made of __________ steel bars.
Hot rolled mild
Cold rolled mild
Forged
Machinable stainless
__________ property of a material is determined by the Herbert Pendulum device.
Hardness
Tensile
Toughness
Compressive
The lightest non-inflammable gas is
H2
He
Ar
O2
__________ glass is used in the mercury in glass thermometer meant for measuring a temperature of 500°C.
Borosilicate
High silica
Supermax
Lead
The co-ordination number in simple cubic structure is
4
6
8
12
Use of water as a manometric liquid suffers from the disadvantage of its
Low vapour pressure
Corrosive nature
High vapour pressure
High boiling point
Which of the following is normally not found in both the S.I. (petrol) & C.I. (diesel) engines?
Air filter
Fuel injector
Exhaust silencer
Battery