Full-Length Mock Test 4 — RRB JE CBT 2 Technical Abilities Pattern (100 MCQs)

Section A: Engineering Mechanics and Strength of Materials (20 Questions)

1. The resultant of two forces acting at an angle is found using the:
   (a) Parallelogram law of forces (b) Ohm's law (c) Bernoulli's equation (d) Stefan-Boltzmann law
2. Lami's theorem applies to a system of:
   (a) Three coplanar, concurrent forces in equilibrium (b) Any number of non-concurrent forces (c) Only a single force (d) Only forces acting on a rigid body in motion, never in equilibrium
3. The centre of gravity of a body is the point at which the:
   (a) Entire weight of the body may be assumed to act (b) Body's temperature is measured (c) Body's electrical charge is concentrated (d) Body's magnetic field originates
4. Kinetic friction acts on a body that is:
   (a) Already in relative sliding motion (b) Completely at rest with no tendency to move (c) In free fall with no contact surface (d) Submerged in a frictionless fluid
5. The coefficient of friction is defined as the ratio of:
   (a) Limiting friction force to normal reaction (b) Normal reaction to limiting friction force (c) Applied force to body weight (d) Body weight to contact area
6. Strain is defined as:
   (a) Deformation per unit original length (b) Force per unit area (c) Energy per unit volume (d) Force per unit volume
7. A ductile material, when tested in tension, typically shows significant:
   (a) Plastic deformation (elongation) before fracture (b) No deformation of any kind before fracture (c) Fracture occurring exactly at the elastic limit with no plastic region (d) Only elastic behaviour with no plastic behaviour ever
8. A brittle material, when tested in tension, typically fractures:
   (a) With little or no plastic deformation (b) Only after extensive plastic deformation identical to ductile materials (c) Only under pure compression, never tension (d) Only at absolute zero temperature
9. The proof resilience of a material is the:
   (a) Maximum energy stored within the elastic limit without permanent deformation (b) Total energy absorbed until fracture (c) Energy released during plastic deformation only (d) Energy required to melt the material
10. Toughness of a material represents its ability to absorb energy:
    (a) Up to fracture, including plastic deformation (b) Only within the elastic limit, with no plastic contribution (c) Only under pure torsion, never other loading (d) Only at cryogenic temperatures
11. The point of contraflexure in a beam is the point where the bending moment:
    (a) Changes sign (from sagging to hogging or vice versa) (b) Is always at its maximum absolute value (c) Is always exactly at the beam's midpoint regardless of loading (d) Is undefined for any beam
12. A beam subjected to pure bending develops maximum bending stress at the:
    (a) Extreme fibres, farthest from the neutral axis (b) Neutral axis itself (c) Exact geometric centre of the cross-section only if it coincides with the neutral axis, with no other case possible (d) Point of zero shear force only
13. The neutral axis of a beam in bending is the axis where the bending stress is:
    (a) Zero (b) Maximum in tension (c) Maximum in compression (d) Undefined
14. A propped cantilever beam has a combination of support conditions consisting of:
    (a) A fixed support at one end and a simple support at the other (b) Simple supports at both ends only (c) Fixed supports at both ends only (d) No supports at all
15. The maximum shear stress theory (Tresca's theory) is commonly used for predicting yielding in:
    (a) Ductile materials (b) Brittle materials exclusively (c) Only perfectly elastic materials with no yielding possible (d) Only materials at absolute zero temperature
16. The maximum principal stress theory (Rankine's theory) is commonly used for predicting failure in:
    (a) Brittle materials (b) Ductile materials exclusively (c) Only fluids, never solids (d) Only gases
17. A close-coiled helical spring under axial load is primarily subjected to:
    (a) Torsional shear stress in the wire (b) Pure bending stress only (c) Pure axial tensile stress only, with no shear (d) No stress at all under load
18. The strain energy stored in a body due to gradually applied load is given by the area under the:
    (a) Load-deflection (or stress-strain) curve up to that load (b) Time-velocity curve (c) Temperature-pressure curve (d) Frequency-amplitude curve
19. A composite (compound) bar made of two different materials, rigidly connected and subjected to a common temperature change, develops thermal stresses because the materials have:
    (a) Different coefficients of thermal expansion (b) Identical coefficients of thermal expansion always (c) No thermal expansion at all in either material (d) Different colours only, with no expansion-related cause
20. The polar moment of inertia of a circular shaft's cross-section is used in calculations involving:
    (a) Torsional stress and angle of twist (b) Bending stress only, with no relation to torsion (c) Axial (direct) stress only (d) Thermal stress only

Section B: Thermodynamics, IC Engines, and Power Plant Engineering (20 Questions)

21. A thermodynamic system that can exchange both matter and energy with its surroundings is called a(n):
    (a) Open system (b) Closed system, exchanging matter but not energy (c) Isolated system (d) Rigid system with no boundary at all
22. A closed thermodynamic system can exchange energy with its surroundings but not:
    (a) Matter (b) Heat specifically, though work exchange is allowed (c) Work specifically, though heat exchange is allowed (d) Any property whatsoever
23. An isolated system exchanges with its surroundings:
    (a) Neither matter nor energy (b) Only matter, no energy (c) Only energy, no matter (d) Both matter and energy freely
24. Specific heat at constant volume (Cv) and specific heat at constant pressure (Cp) for an ideal gas are related by:
    (a) Cp − Cv = R (the specific gas constant) (b) Cp = Cv always, with no difference (c) Cp × Cv = R (d) Cp/Cv = 0 always
25. The ratio of specific heats (Cp/Cv), denoted γ, for a diatomic ideal gas is approximately:
    (a) 1.4 (b) 1.0 (c) 2.0 (d) 0.4
26. In an internally reversible process, the system passes through a series of:
    (a) Equilibrium states, with no dissipative effects (b) Highly non-equilibrium, chaotic states only (c) States with infinite entropy generation (d) States identical regardless of process path
27. The Carnot cycle consists of two isothermal processes and two:
    (a) Adiabatic (isentropic) processes (b) Isobaric processes (c) Isochoric processes (d) Polytropic processes with n=0 only
28. A diesel engine generally operates at a higher compression ratio than a petrol engine, primarily because diesel engines:
    (a) Compress air alone (no fuel), avoiding the risk of premature auto-ignition seen with a pre-mixed charge (b) Use a much weaker fuel with lower energy content (c) Operate at much lower speeds than petrol engines in every case (d) Have no piston or cylinder at all
29. Detonation (knocking) in a spark-ignition engine is caused by:
    (a) Uncontrolled, spontaneous auto-ignition of the end-gas ahead of the advancing flame front (b) Complete absence of any combustion (c) Excessively low compression ratio only, with no other cause (d) Using only pure air with no fuel present
30. Octane number is a measure of a petrol fuel's resistance to:
    (a) Knocking (detonation) (b) Evaporation at low temperature (c) Corrosion of the fuel tank (d) Viscosity change with temperature
31. Cetane number is a measure of a diesel fuel's:
    (a) Ignition quality (readiness to self-ignite) (b) Resistance to knocking, exactly like octane number for petrol (c) Viscosity at low temperature only (d) Colour and odour
32. The scavenging process in a two-stroke engine refers to:
    (a) Removing burnt exhaust gases and replacing them with fresh charge (b) Removing lubricating oil from the crankcase (c) Cooling the cylinder head with external water spray (d) Cleaning the fuel tank of sediment
33. A radiator in an IC engine's cooling system is used to:
    (a) Dissipate heat from the engine coolant to the atmosphere (b) Generate additional power from waste heat (c) Compress the intake air (d) Store fuel for later use
34. The lubrication system in an IC engine primarily serves to:
    (a) Reduce friction and wear between moving parts, and assist in cooling (b) Increase friction deliberately for braking purposes (c) Ignite the air-fuel mixture (d) Filter the intake air only
35. The Otto cycle's thermal efficiency depends primarily on the:
    (a) Compression ratio (b) Ambient humidity only (c) Fuel's exact chemical formula only, with no thermodynamic dependence (d) Engine's paint colour
36. In a vapour power cycle, the "reheat" modification involves:
    (a) Expanding steam partially, then reheating it before further expansion, to improve efficiency and reduce moisture at turbine exhaust (b) Reheating the condenser cooling water only, with no effect on the cycle (c) Removing the boiler entirely from the cycle (d) Doubling the condenser pressure with no other change
37. Regenerative feed heating in a Rankine cycle involves:
    (a) Using steam bled from the turbine to preheat the boiler feedwater (b) Discarding all extracted steam without any use (c) Cooling the boiler feedwater to below ambient temperature (d) Removing the feed pump entirely from the cycle
38. A hydroelectric power plant converts the potential energy of stored water into:
    (a) Kinetic energy (via a turbine), then into electrical energy (b) Nuclear energy directly (c) Chemical energy directly (d) Thermal energy exclusively, with no turbine or generator involved
39. A pumped storage hydroelectric scheme is used primarily to:
    (a) Store surplus electrical energy by pumping water to a higher reservoir for later generation (b) Generate power only during flood conditions (c) Eliminate the need for any generator or turbine (d) Permanently consume electrical energy with no later recovery
40. Combined cycle power plants improve overall efficiency by:
    (a) Using waste heat from a gas turbine's exhaust to generate steam for an additional steam turbine (b) Running two identical gas turbines with no heat recovery at all (c) Eliminating the need for any turbine (d) Operating only on nuclear fuel with no gas or steam cycle involved

Section C: Theory of Machines and Machine Design (20 Questions)

41. A kinematic pair in which the relative motion between the two links is purely sliding is called a:
    (a) Sliding pair (b) Turning (revolute) pair (c) Rolling pair (d) Spherical pair
42. A kinematic pair in which the relative motion between the two links is purely rotational about a fixed axis is called a:
    (a) Turning (revolute) pair (b) Sliding pair (c) Screw pair (d) Spherical pair
43. Grubler's equation (or the Kutzbach criterion) is used to determine the:
    (a) Degree of freedom (mobility) of a planar mechanism (b) Exact weight of the mechanism (c) Colour scheme of the mechanism's components (d) Manufacturing cost of the mechanism
44. A quick-return mechanism, commonly used in shaping machines, is designed so that the:
    (a) Return stroke is completed in less time than the cutting (forward) stroke (b) Forward and return strokes always take exactly equal time (c) Return stroke never actually occurs, with the mechanism operating one-way only (d) Tool remains stationary throughout the entire cycle
45. In a Whitworth quick-return mechanism, the ratio of times taken for the cutting and return strokes depends on the:
    (a) Geometric proportions (link lengths) of the mechanism (b) Ambient temperature only, with no relation to geometry (c) Colour of the mechanism's links (d) Operator's skill level only, with no mechanical basis
46. The velocity of a point on a rigid link, relative to another point on the same link, is always:
    (a) Perpendicular to the line joining the two points (b) Parallel to the line joining the two points (c) Zero at all times regardless of motion (d) Equal in magnitude and direction to the absolute velocity of either point
47. The instantaneous centre of rotation of a rigid body in plane motion is the point that:
    (a) Has zero velocity at that instant (b) Has maximum velocity at that instant (c) Lies at the body's centre of mass at all times (d) Is undefined for any rigid body motion
48. Kennedy's theorem, used in velocity analysis of mechanisms, states that three bodies with relative plane motion have their instantaneous centres:
    (a) Lying on a straight line (b) Forming an equilateral triangle in every case (c) Coinciding at a single point in every case (d) Located at infinity in every case
49. A cam profile designed for uniform velocity motion of the follower produces a follower displacement diagram that is:
    (a) A straight line (linear with cam angle) during the rise/fall period (b) A perfect sine curve throughout (c) A perfect parabola throughout (d) A step function with instantaneous jumps
50. Simple harmonic motion (SHM) of a follower, used in certain cam designs, produces displacement that varies as a:
    (a) Sine (or cosine) function of the cam angle (b) Straight line, exactly like uniform velocity motion (c) Random, unpredictable function (d) Step function with instantaneous jumps
51. Jump (or follower bounce) in a cam mechanism occurs when the follower:
    (a) Loses contact with the cam surface at high speed due to inertia effects (b) Moves exactly as prescribed by the cam profile with no deviation, at any speed (c) Remains permanently in contact regardless of speed or spring force (d) Is removed entirely from the mechanism
52. The static balancing condition for a system of rotating masses requires the vector sum of the centrifugal forces to be:
    (a) Zero (b) Equal to the total system weight (c) Maximum possible (d) Undefined, with no specific condition
53. Balancing of reciprocating masses (as in an IC engine) aims to reduce:
    (a) The unbalanced primary and secondary inertia forces (b) The engine's fuel consumption directly, with no relation to forces (c) The number of cylinders required (d) The engine's ignition timing
54. Whirling (critical) speed of a rotating shaft is the speed at which the shaft:
    (a) Exhibits large, potentially dangerous lateral vibrations due to resonance (b) Runs perfectly smoothly with zero vibration under all conditions (c) Cannot rotate at all due to complete mechanical lock-up (d) Reverses its direction of rotation spontaneously
55. A gear tooth's "addendum" is the radial distance from the pitch circle to the:
    (a) Tooth tip (addendum circle) (b) Tooth root (dedendum circle) (c) Gear's centre (d) Base circle only, with no relation to the tooth tip
56. A gear tooth's "dedendum" is the radial distance from the pitch circle to the:
    (a) Tooth root (dedendum circle) (b) Tooth tip (addendum circle) (c) Gear's outer casing (d) Base circle exclusively, with no relation to the tooth root
57. The design of a shaft under combined bending and torsion commonly uses the concept of:
    (a) Equivalent bending moment and equivalent torque (b) Only the bending moment, ignoring torque entirely (c) Only the torque, ignoring bending entirely (d) Neither bending nor torque, only axial load
58. A cotter joint is a temporary fastening method used to connect:
    (a) Two rods subjected to axial tensile or compressive load (b) Two gears meshing at right angles (c) Two electrical conductors only (d) Two hydraulic pipes carrying fluid, with no mechanical load
59. A knuckle joint is commonly used to connect two rods subjected to axial tensile load where a small amount of:
    (a) Angular movement (articulation) between the rods is required (b) Rotational speed difference of thousands of RPM is required (c) Electrical isolation is required, with no mechanical connection at all (d) Thermal insulation is required, with no mechanical connection at all
60. The design of a riveted joint considers failure modes including tearing of the plate, shearing of the rivet, and:
    (a) Crushing (bearing) failure of the plate/rivet (b) Only electrical failure, with no mechanical failure mode considered (c) Only thermal failure, with no mechanical failure mode considered (d) Only magnetic failure, with no mechanical failure mode considered

Section D: Fluid Mechanics, Manufacturing, Metrology, Heat Transfer, and Material Science (20 Questions)

61. The continuity equation in fluid mechanics expresses the principle of conservation of:
    (a) Mass (b) Electrical charge (c) Magnetic flux (d) Chemical composition
62. Reynolds number is used to determine whether a fluid flow is:
    (a) Laminar or turbulent (b) Compressible or incompressible only, with no relation to flow regime (c) Steady or unsteady only, with no relation to flow regime (d) Rotational or irrotational only, with no relation to flow regime
63. A flow with a Reynolds number below the critical value (for pipe flow, typically around 2000) is generally:
    (a) Laminar (b) Turbulent (c) Supersonic (d) Undefined
64. A reciprocating pump, unlike a centrifugal pump, moves fluid by means of a:
    (a) Piston moving within a cylinder, displacing fluid directly (b) Rotating impeller imparting kinetic energy to the fluid (c) Rotating fan blade moving air only, never liquid (d) Stationary diaphragm with no moving parts at all
65. Cavitation in a centrifugal pump occurs when the local pressure falls below the fluid's:
    (a) Vapour pressure, causing vapour bubbles to form and then collapse (b) Boiling point at standard atmospheric pressure only, regardless of local pressure (c) Freezing point, causing ice formation (d) Critical pressure at the triple point exclusively
66. Forging is a manufacturing process in which metal is shaped by:
    (a) Applying compressive force (hammering or pressing) (b) Melting and pouring into a mould (c) Removing material via a rotating cutting tool (d) Joining two pieces using an electric arc
67. Extrusion is a manufacturing process in which metal is forced through a die to produce a:
    (a) Product with a constant cross-sectional profile along its length (b) Product with a randomly varying cross-section (c) Hollow sphere only, with no other shape possible (d) Product with zero length
68. Drilling is a machining operation primarily used to produce:
    (a) Cylindrical holes in a workpiece (b) Flat surfaces only, with no hole production (c) External threads only, with no hole production (d) Gear teeth exclusively
69. Grinding is a machining process that uses an abrasive wheel to achieve:
    (a) Fine surface finish and close dimensional accuracy (b) Only rough, large-scale material removal with no finish improvement (c) Joining of two separate workpieces (d) Heat treatment of the workpiece with no material removal
70. A comparator, as used in metrology, is an instrument that:
    (a) Shows the deviation of a dimension from a preset reference, rather than an absolute measurement (b) Always provides an absolute measurement with no reference needed (c) Measures only electrical resistance (d) Measures only temperature
71. A sine bar is used to accurately measure or set up:
    (a) Angles, using trigonometric principles (b) Only linear length, with no angular capability (c) Only surface roughness (d) Only material hardness
72. Convection heat transfer between a solid surface and a moving fluid is governed by:
    (a) Newton's law of cooling (b) Fourier's law, exclusively (c) Stefan-Boltzmann law, exclusively (d) Pascal's law
73. Radiative heat transfer between two surfaces increases sharply with:
    (a) Absolute temperature (proportional to its fourth power for a black body) (b) Only surface colour, with no temperature dependence (c) Only surface roughness, with no temperature dependence (d) Only the surrounding fluid's viscosity
74. A vapour compression refrigeration cycle's expansion device (such as a thermostatic expansion valve) primarily serves to:
    (a) Throttle high-pressure liquid refrigerant to a low pressure/temperature (b) Compress low-pressure vapour to high pressure (c) Reject heat to the surroundings (d) Absorb heat from the space being cooled
75. Body-centred cubic (BCC) crystal structure, found in iron at room temperature, generally gives:
    (a) High strength with somewhat reduced ductility compared to FCC (b) Extremely low strength with no practical use (c) Perfect ductility with zero strength (d) No crystalline order at all
76. Case hardening processes such as carburising are used to produce a component with a:
    (a) Hard, wear-resistant surface and a tough, ductile core (b) Uniformly soft surface throughout, with no hardening at all (c) Completely non-metallic surface coating (d) Reduced overall strength compared to the untreated component
77. Titanium alloys, despite their higher cost, are favoured in aerospace applications primarily for their:
    (a) Excellent strength-to-weight ratio and corrosion resistance (b) Extremely low cost compared to aluminium (c) Complete absence of any practical engineering use (d) High density compared to steel, aiding stability
78. A plate heat exchanger, compared to a shell-and-tube design, generally offers a:
    (a) More compact size for a given heat transfer area (b) Much larger physical footprint for equivalent duty (c) No heat transfer capability at all (d) Function only as a structural support, with no thermal role
79. Psychrometry is the study of the properties of:
    (a) Moist air (mixtures of dry air and water vapour) (b) Pure metals only, with no relation to air or moisture (c) Lubricating oils only (d) Nuclear fuel rods only
80. The dew point temperature of moist air is the temperature at which the air:
    (a) Becomes saturated and begins to condense moisture upon further cooling (b) Reaches its maximum possible temperature under any condition (c) Becomes completely dry with zero moisture content (d) Freezes solid regardless of pressure

Section E: General Awareness, Computer Applications, and Current Affairs (20 Questions)

81. The Central Board of Secondary Education (CBSE), sometimes referenced in general awareness sections, functions under which ministry?
    (a) Ministry of Education (b) Ministry of Railways (c) Ministry of Defence (d) Ministry of Finance
82. The full form of "GUI" in computing is:
    (a) Graphical User Interface (b) General Utility Interface (c) Global Unified Index (d) Graphic Unit Identifier
83. In MS Excel, the function used to sum a range of cells is:
    (a) SUM() (b) TOTAL() (c) ADDUP() (d) COUNT()
84. The full form of "PDF" is:
    (a) Portable Document Format (b) Personal Data File (c) Printed Document Format (d) Program Data Format
85. Cloud computing refers to the delivery of computing services primarily over the:
    (a) Internet, from remote servers (b) A dedicated local cable only, with no internet involved (c) Postal mail system (d) Landline telephone network only
86. A computer "virus" is best described as:
    (a) Malicious software that can replicate and spread, potentially harming systems/data (b) A hardware component that improves processing speed (c) A type of antivirus protection program (d) An authorised system update
87. Make in India, National Manufacturing Policy, and Skill India together broadly support India's efforts toward:
    (a) Strengthening domestic industrial capacity and employability (b) Discouraging any industrial growth (c) Eliminating vocational training entirely (d) Applying only to the IT sector, with no relevance to manufacturing
88. The Indian Railways is administratively divided into zones, each headed by a:
    (a) General Manager (b) Prime Minister (c) Chief Justice (d) Governor
89. The Research Designs and Standards Organisation (RDSO) of Indian Railways is primarily responsible for:
    (a) Research, design, and standardisation of railway equipment and practices (b) Ticket booking and reservation only (c) Catering services on trains only (d) Postal parcel delivery
90. The Vande Bharat Express, a notable modern Indian train, is significant for being:
    (a) A semi-high-speed, indigenously manufactured train set (b) A steam-powered train reintroduced for heritage tourism only (c) Operated exclusively outside India, with no domestic routes (d) A cargo-only freight train with no passenger service
91. Dedicated Freight Corridors (DFCs) being developed by Indian Railways aim to:
    (a) Provide dedicated freight-only rail routes, decongesting passenger lines (b) Eliminate all freight transport by rail entirely (c) Serve only international freight, with no domestic relevance (d) Replace all passenger trains with freight trains on existing lines
92. The "Make in India" logo is represented by a stylised image of a:
    (a) Lion, made of gears (b) Elephant (c) Peacock (d) Tiger
93. Digital India, as a broad government initiative, includes objectives such as:
    (a) Universal digital literacy and expanded digital infrastructure (b) Elimination of all physical infrastructure (c) Restriction of internet access to select cities only (d) Discontinuing all e-governance services
94. The Atal Innovation Mission primarily aims to promote:
    (a) Innovation and entrepreneurship, including through Atal Tinkering Labs in schools (b) Only agricultural subsidy distribution (c) Only currency exchange regulation (d) Only railway ticket pricing policy
95. The National Apprenticeship Promotion Scheme aims to:
    (a) Encourage industry to engage apprentices for practical skill development (b) Discourage any apprenticeship training (c) Apply only to government offices, with no industry relevance (d) Eliminate the need for formal technical education entirely
96. The term "Industry 4.0" is closely associated with technologies such as:
    (a) IoT, big data, and automation in manufacturing (b) Only manual assembly line methods with no automation (c) Only 19th-century steam engines (d) Only agricultural tools with no manufacturing relevance
97. Automated Teller Machines (ATMs), a common example of automation in daily life, are primarily used for:
    (a) Banking transactions such as cash withdrawal (b) Only railway ticket printing (c) Only postal stamp dispensing (d) Only vehicle registration
98. E-governance initiatives in India aim to make government services more:
    (a) Accessible, transparent, and efficient through digital delivery (b) Restricted and less accessible to citizens (c) Available only through in-person visits with no digital option (d) Dependent solely on postal correspondence
99. The "One Nation One Card" initiative in India relates to:
    (a) A unified payment/transit card usable across multiple services (b) A single national identity document replacing all others entirely (c) A single railway zone replacing all existing zones (d) A single electricity grid replacing all regional grids
100. Engineering education and technical training bodies in India, such as the All India Council for Technical Education (AICTE), primarily regulate:
     (a) Technical and management education standards (b) Railway safety standards exclusively (c) Currency printing standards (d) Postal service standards

Answer Key with Explanations

1.(a) The parallelogram law finds the resultant of two forces at an angle.

2.(a) Lami's theorem applies to three coplanar concurrent forces in equilibrium.

3.(a) The centre of gravity is where the total weight may be assumed to act.

4.(a) Kinetic friction acts on a body already sliding.

5.(a) Coefficient of friction = limiting friction / normal reaction.

6.(a) Strain = deformation / original length.

7.(a) Ductile materials show significant plastic elongation before fracture.

8.(a) Brittle materials fracture with little/no plastic deformation.

9.(a) Proof resilience is the max energy stored within the elastic limit.

10.(a) Toughness is energy absorbed up to fracture, including plastic deformation.

11.(a) A point of contraflexure is where bending moment changes sign.

12.(a) Maximum bending stress occurs at extreme fibres.

13.(a) The neutral axis has zero bending stress.

14.(a) A propped cantilever has one fixed and one simple support.

15.(a) Maximum shear stress theory suits ductile materials.

16.(a) Maximum principal stress theory suits brittle materials.

17.(a) A close-coiled helical spring under axial load is mainly in torsional shear.

18.(a) Strain energy = area under the load-deflection curve.

19.(a) Thermal stresses in compound bars arise from differing expansion coefficients.

20.(a) Polar moment of inertia is used in torsional stress/twist calculations.

21.(a) An open system exchanges both matter and energy.

22.(a) A closed system exchanges energy but not matter.

23.(a) An isolated system exchanges neither matter nor energy.

24.(a) Cp − Cv = R for an ideal gas.

25.(a) γ ≈ 1.4 for a diatomic ideal gas.

26.(a) Internally reversible processes pass through equilibrium states.

27.(a) The Carnot cycle has two isothermal and two adiabatic processes.

28.(a) Diesel engines compress air alone, avoiding pre-ignition risk, allowing higher compression ratio.

29.(a) Knocking is caused by uncontrolled auto-ignition of the end-gas.

30.(a) Octane number measures resistance to knocking.

31.(a) Cetane number measures diesel ignition quality.

32.(a) Scavenging removes exhaust gases and replaces them with fresh charge.

33.(a) A radiator dissipates engine coolant heat to atmosphere.

34.(a) Lubrication reduces friction/wear and assists cooling.

35.(a) Otto cycle efficiency depends on compression ratio.

36.(a) Reheat re-expands steam after partial expansion, improving efficiency/reducing moisture.

37.(a) Regenerative feed heating uses bled steam to preheat feedwater.

38.(a) Hydro plants convert water's PE into KE via turbine, then electrical energy.

39.(a) Pumped storage stores surplus energy by pumping water to a higher reservoir.

40.(a) Combined cycle plants use gas turbine exhaust heat for an additional steam cycle.

41.(a) A sliding pair has purely sliding relative motion.

42.(a) A turning (revolute) pair has purely rotational relative motion.

43.(a) Grubler's/Kutzbach criterion determines mechanism mobility.

44.(a) A quick-return mechanism completes the return stroke faster than the cutting stroke.

45.(a) The Whitworth mechanism's stroke time ratio depends on its link geometry.

46.(a) Relative velocity between points on a rigid link is perpendicular to the line joining them.

47.(a) The instantaneous centre has zero velocity at that instant.

48.(a) Kennedy's theorem: three instantaneous centres lie on a straight line.

49.(a) Uniform velocity cam motion gives a linear displacement diagram.

50.(a) SHM follower motion varies as a sine/cosine function of cam angle.

51.(a) Follower jump occurs from loss of contact at high speed due to inertia.

52.(a) Static balance requires the centrifugal force vector sum to be zero.

53.(a) Reciprocating mass balancing reduces unbalanced primary/secondary inertia forces.

54.(a) Whirling speed causes large lateral vibrations due to resonance.

55.(a) Addendum is the radial distance from pitch circle to tooth tip.

56.(a) Dedendum is the radial distance from pitch circle to tooth root.

57.(a) Combined bending-torsion shaft design uses equivalent bending moment/torque.

58.(a) A cotter joint connects rods under axial tensile/compressive load.

59.(a) A knuckle joint allows a small angular movement between connected rods.

60.(a) Riveted joint failure modes include plate tearing, rivet shearing, and crushing.

61.(a) The continuity equation expresses conservation of mass.

62.(a) Reynolds number determines laminar vs. turbulent flow.

63.(a) Below critical Reynolds number (~2000 for pipes), flow is laminar.

64.(a) A reciprocating pump uses a piston displacing fluid directly.

65.(a) Cavitation occurs when local pressure falls below vapour pressure.

66.(a) Forging shapes metal via compressive force.

67.(a) Extrusion produces a constant cross-section product through a die.

68.(a) Drilling produces cylindrical holes.

69.(a) Grinding achieves fine finish and close dimensional accuracy.

70.(a) A comparator shows deviation from a preset reference.

71.(a) A sine bar measures/sets angles using trigonometry.

72.(a) Convection is governed by Newton's law of cooling.

73.(a) Radiative transfer increases sharply with absolute temperature (T⁴ for black body).

74.(a) An expansion device throttles high-pressure liquid to low pressure/temperature.

75.(a) BCC gives high strength with somewhat reduced ductility vs. FCC.

76.(a) Case hardening gives a hard surface with a tough core.

77.(a) Titanium alloys offer excellent strength-to-weight ratio and corrosion resistance.

78.(a) Plate heat exchangers are more compact for a given heat transfer area.

79.(a) Psychrometry studies moist air properties.

80.(a) Dew point is where air becomes saturated and begins to condense.

81.(a) CBSE functions under the Ministry of Education.

82.(a) GUI stands for Graphical User Interface.

83.(a) SUM() sums a range of cells in Excel.

84.(a) PDF stands for Portable Document Format.

85.(a) Cloud computing delivers services over the internet from remote servers.

86.(a) A computer virus is malicious, replicating software causing harm.

87.(a) These initiatives support domestic industrial capacity and employability.

88.(a) Each railway zone is headed by a General Manager.

89.(a) RDSO handles research, design, and standardisation for Indian Railways.

90.(a) Vande Bharat Express is a semi-high-speed, indigenously manufactured train.

91.(a) DFCs provide dedicated freight routes, decongesting passenger lines.

92.(a) The Make in India logo is a lion made of gears.

93.(a) Digital India includes universal digital literacy and infrastructure goals.

94.(a) Atal Innovation Mission promotes innovation/entrepreneurship, including Tinkering Labs.

95.(a) The National Apprenticeship Promotion Scheme encourages industry apprenticeship engagement.

96.(a) Industry 4.0 involves IoT, big data, and automation.

97.(a) ATMs are used for banking transactions like cash withdrawal.

98.(a) E-governance aims for accessible, transparent, efficient digital service delivery.

99.(a) "One Nation One Card" is a unified payment/transit card.

100.(a) AICTE regulates technical and management education standards.