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Past Questions — 2012
The iron that exists between 910ºC and 1405ºC is termed as
A)
α-iron
B)
β-iron
C)
γ-iron
D)
δ-iron
Iron exists in different allotropic forms at different temperature ranges. Between about 910°C and 1405°C, iron is in the gamma form, called γ-iron or austenite. α-iron exists below 910°C, and δ-iron exists above about 1405°C up to the melting point. Therefore, the correct answer is γ-iron.
Short range crystalline lattice structure is generally observed in
A)
thermoplastics
B)
composites
C)
refractories
D)
thermosetting plastics
Short-range crystalline lattice structure is generally associated with thermosetting plastics because their highly cross-linked molecular network restricts long-range order but can show limited local arrangement. Thermoplastics are usually more amorphous or only partially crystalline, composites are a broad class and not defined by this feature, and refractories are not typically identified by short-range crystalline lattice structure in this context.
Temperature at which solid glass changes to liquid glass is
A)
softening temperature
B)
transition temperature
C)
critical temperature
D)
none of the above
In glass technology, the temperature at which solid glass begins to behave like a liquid and changes from a rigid state to a plastic/liquid state is called the transition temperature.
- Softening temperature: the temperature at which glass starts to soften under its own weight, but this is not the standard term for the solid-to-liquid change.
- Critical temperature: not the correct term in glass materials context.
- Therefore, the correct answer is transition temperature.
An allotropic material should have
A)
fixed structure at all temperature
B)
different structures at different temperature
C)
atoms distributed in random patterns
D)
none of the above
Allotropy is the property of an element to exist in two or more different structural forms in the same physical state, often depending on temperature or pressure. So an allotropic material should have different structures at different temperatures. Option (a) is wrong because a fixed structure at all temperatures is not allotropy. Option (c) describes an amorphous/random arrangement, not allotropy. Hence, (b) is correct.
The reason for low productivity of an organization is
A)
poor product design
B)
lack of standardization
C)
improper cutting tools
D)
all of these
Low productivity in an organization can result from poor product design, which makes manufacturing inefficient; lack of standardization, which increases variation and waste; and improper cutting tools, which reduce speed, accuracy, and output. Since all three factors contribute to low productivity, the correct answer is 'all of these'.
The basic drive systems usually used in commercially available robots is
A)
hydraulic
B)
electric motor
C)
pneumatic
D)
all the above
Commercially available robots usually use electric motors as the basic drive system because they are compact, efficient, easy to control, and suitable for precise motion. Hydraulic drives are used mainly where very high force is needed, and pneumatic drives are simpler but less precise. Therefore, the correct answer is electric motor.
The process of reducing the ore with carbon in the presence of a flux is called
A)
annealing
B)
smelting
C)
carbonation
D)
hardening
Smelting is the process of extracting a metal from its ore by heating and reducing it with carbon, usually in the presence of a flux to remove impurities as slag. Annealing and hardening are heat-treatment processes for metals, while carbonation is unrelated to ore reduction.
The bond formed by sharing of atoms is called
A)
covalent bond
B)
ionic bond
C)
metallic bond
D)
coordinate bond
A bond formed by sharing of electrons between atoms is called a covalent bond. Ionic bond involves transfer of electrons, metallic bond is the bonding in metals, and coordinate bond is a special type of covalent bond where both shared electrons come from one atom.
Strength is the ability of the material to resist
A)
deformation under stress
B)
externally applied forces with breakdown
C)
fracture due to high impact load
D)
none of the above
Strength is the ability of a material to resist an applied load or force without failure. Among the options, this is best matched by (b) externally applied forces with breakdown. Option (a) describes stiffness or rigidity, not strength. Option (c) refers specifically to impact resistance or toughness. Hence, (b) is correct.
The process used for relieving the internal stresses previously set up in the metal and for increasing the machinability of steel is
A)
normalizing
B)
full annealing
C)
process annealing
D)
spheroidising
Process annealing is used to relieve internal stresses developed in metal during cold working and to improve machinability, especially in low-carbon steels. Normalizing mainly refines grain structure and increases strength; full annealing softens steel but is not specifically the standard process for relieving cold-work stresses and improving machinability in this context; spheroidising is mainly used to improve machinability of high-carbon steels by making cementite spherical.
The most advanced commercial language designed for use with robots is
A)
VAL
B)
REL
C)
ROBOTICA
D)
ROB
VAL (Victor’s Assembly Language) is a well-known early robot programming language and is commonly cited in robotics MCQs as the most advanced commercial language designed for use with robots. REL, ROBOTICA, and ROB are not the standard answer in such exam contexts. Hence, the correct option is VAL.
Vacancy arises in a crystal due to
A)
missing atoms
B)
presence of extra atoms
C)
presence of foreign particles
D)
none of these
A vacancy defect in a crystal is formed when one or more atoms are missing from their normal lattice positions. This creates an empty lattice site called a vacancy. Extra atoms would cause interstitial defects, and foreign particles would cause impurity defects, not vacancy defects.
The problem of line balancing is particularly important in
A)
product layout
B)
process layout
C)
combined layout
D)
matrix layout
Line balancing is mainly concerned with arranging work elements so that each workstation in a production line has nearly equal workload. This is especially important in a product layout, where machines and workstations are arranged according to the sequence of operations for a specific product. In process layout, jobs follow different routes, so line balancing is not the central issue. Combined and matrix layouts are not the standard context for line balancing.
Normal distribution of the project completion time is assumed to follow in
A)
CPM
B)
PERT
C)
both CPM and PERT
D)
none of these
PERT assumes that activity times are probabilistic and that the project completion time follows a normal distribution approximately. CPM, on the other hand, uses deterministic activity times and does not assume a normal distribution. Therefore, the correct answer is PERT.
The process of lowering the hardness and tensile strength but improving the machinability of steels is
A)
normalizing
B)
quenching
C)
annealing
D)
spheroidising
Annealing is the heat treatment used to soften steel. It lowers hardness and tensile strength and generally improves ductility and machinability by producing a softer, more uniform structure. Normalizing usually increases strength and hardness compared to annealing, quenching greatly increases hardness, and spheroidising is mainly used for high-carbon steels to improve machinability, but the standard general process described here is annealing.
Micro-structure of a material is generally examined by
A)
optical microscope
B)
X-ray technique
C)
spectroscope
D)
none of the above
Micro-structure refers to the internal structure of a material at microscopic scale, such as grains, phases, and defects. It is generally examined using an optical microscope after proper specimen preparation and etching. X-ray techniques are mainly used for crystal structure and phase analysis, while a spectroscope is used for studying spectra, not microstructure.
The packing of atoms in hexagonal closed packed lattice is
A)
maximum
B)
minimum
C)
moderate
D)
none of the above
In a hexagonal close packed (HCP) lattice, atoms are packed as closely as possible, giving the highest packing efficiency among common crystal structures. Therefore, the packing of atoms in HCP lattice is maximum. The other options are incorrect because HCP is not minimum or moderate packing.
The type of space lattice found in gamma-iron is
A)
close packed hexagonal space lattice
B)
body centred cubic space lattice
C)
face centred cubic space lattice
D)
none of the above
Gamma-iron (γ-iron), also called austenite, has a face-centred cubic (FCC) crystal structure. In contrast, alpha-iron is body-centred cubic (BCC), and close-packed hexagonal is not the structure of iron in the gamma phase. Therefore, the correct option is (c).
Due to standardization, the total cost of the product is
A)
reduced
B)
increased
C)
unaffected
D)
none of these
Standardization means using uniform specifications, sizes, and methods. This reduces variety, simplifies production, lowers setup and inventory costs, and improves interchangeability. Hence, the total cost of the product is generally reduced. The other options are incorrect because standardization does not usually increase cost or leave it unaffected.
When the length of the journal is equal to the diameter of the journal, then the bearing is said to be a
A)
short bearing
B)
long bearing
C)
medium bearing
D)
square bearing
In journal bearing terminology, if the length of the journal is equal to its diameter, the bearing is called a square bearing. A short bearing has length less than diameter, and a long bearing has length greater than diameter. Hence the correct answer is square bearing.
In flange coupling, the bolts are subjected to
A)
tensile stress
B)
compressive stress
C)
shear stress
D)
none of these
In a flange coupling, the torque is transmitted from one shaft to the other through the bolts. This torque tends to shear the bolts across the flange joint, so the bolts are primarily subjected to shear stress. Tensile or compressive stresses are not the main design stresses for the bolts in a standard flange coupling.
The distance of the centroid of a semicircle of radius ‘r’ from its base is
A)
4r/3π
B)
3π/4r
C)
4π/3r
D)
none of these
For a semicircular area of radius r, the centroid lies on the axis of symmetry at a distance 4r/(3π) from the base (diameter). This is a standard result from mechanics of materials/engineering mechanics. Hence option (a) is correct. The other options have the wrong form and dimensions.
The outside diameter of a hollow shaft is twice it’s inside diameter. The ratio of its torque carrying capacity to that of a solid shaft of the same material and the same outside diameter is
A)
15/16
B)
3/4
C)
1/2
D)
1/16
For shafts of the same material and same outside diameter, torque carrying capacity is proportional to the polar section modulus, which is proportional to (D^4 - d^4)/D for a hollow shaft and D^3 for a solid shaft. Let the outside diameter be D and inside diameter be d. Given D = 2d, so d = D/2.
Ratio = (D^4 - d^4) / D^4 = 1 - (d/D)^4 = 1 - (1/2)^4 = 1 - 1/16 = 15/16.
So the hollow shaft carries 15/16 of the torque of the solid shaft. The other options do not match this standard torsion relation.
Surface endurance limit of gear material is dependent upon
A)
elastic strength
B)
coefficient of elasticity
C)
Brinell hardness number
D)
toughness
The surface endurance limit of gear material is mainly related to surface contact fatigue resistance, which correlates with hardness. For gear teeth, higher Brinell hardness number generally means better resistance to pitting and higher surface endurance limit. Elastic strength and toughness are not the governing factors here, and coefficient of elasticity affects elastic deformation rather than surface fatigue strength.
The maximum allowable compressive stress corresponding to lateral buckling in a discretely laterally supported symmetrical I-beam, does not depend upon
A)
modulus of elasticity
B)
radios of gyration about the minor axis
C)
ratio of span and length of beam
D)
ratio of overall depth to thickness of the flange
For lateral buckling of a discretely laterally supported symmetrical I-beam, the allowable compressive stress depends on the material and section properties governing lateral torsional buckling, such as the modulus of elasticity, the radius of gyration about the minor axis, and the effective unbraced span/length. It does not depend directly on the ratio of overall depth to flange thickness; that is not a governing parameter for the lateral buckling stress expression. Hence, option (d) is correct.