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Past Questions
The statement that energy can be neither created nor destroyed but only converted from one form to another, is known as
A)
First law of thermodynamics
B)
Second law of thermodynamics
C)
Avogadro’s hypothesis
D)
Zeroth law of thermodynamics
The statement says energy can neither be created nor destroyed, only converted from one form to another. This is exactly the law of conservation of energy, which is the First law of thermodynamics. The Second law deals with entropy and direction of processes, the Zeroth law defines thermal equilibrium, and Avogadro’s hypothesis is unrelated to thermodynamics.
The general gas equation is
A)
PV=RT
B)
PV=(RT)™
C)
PV=mRT
D)
PV"= constant
The general gas equation for an ideal gas is PV = mRT, where P is pressure, V is volume, m is mass of the gas, R is the specific gas constant, and T is absolute temperature. Option (a) PV = RT is incomplete because it omits mass. Option (b) appears malformed and is not the standard gas equation. Option (d) PV^n = constant is the polytropic relation, not the general gas equation.
120, 101, 82, 65, 50, ?
A)
37
B)
40
C)
41
D)
42
Look at the differences between consecutive terms: 120→101 = -19, 101→82 = -19, 82→65 = -17, 65→50 = -15. The subtraction pattern decreases by 2 each time after repeating -19 once: -19, -19, -17, -15, so the next difference is -13. Therefore, 50 - 13 = 37. Hence the correct answer is 37.
Cost of supervisory charges, depreciation of plant and machinery, consumables, power and lighting charges, office expenses, etc. are termed under
A)
Total cost
B)
Factory cost
C)
Overheads
D)
Direct cost
Supervisory charges, depreciation of plant and machinery, consumables, power and lighting charges, and office expenses are indirect expenses. Such indirect costs are collectively termed as overheads.
Why others are incorrect:
- Total cost includes all costs together, not just these indirect items.
- Factory cost usually includes prime cost plus factory overheads, but the question asks for the general term for these expenses.
- Direct cost refers to expenses directly traceable to a product, which these are not.
The device designed to remove moisture from a refrigerant is called
A)
Dehumidifier
B)
Humidstat
C)
Expansion valve
D)
Drier
A drier is the device used in a refrigeration system to remove moisture from the refrigerant. Moisture can cause ice formation, corrosion, and blockage in the system. A dehumidifier removes moisture from air, not refrigerant. A humidstat is a humidity-controlling switch, and an expansion valve is used to regulate refrigerant flow and pressure drop, not to remove moisture.
If the specific head of a pump is 170 to 400, the type of pump would be
A)
Axial flow
B)
Mixed flow
C)
Radial flow
D)
Turbine type
Pumps are classified by specific head (or specific speed). A low specific head corresponds to a radial flow pump, a medium range to a mixed flow pump, and a high range to an axial flow pump. Since the given specific head is 170 to 400, it falls in the range of a radial flow pump. Axial flow pumps are used for very high specific speed/low head applications, mixed flow pumps are intermediate, and 'turbine type' is not the correct classification here.
In a four wheel drive the number of gear boxes is
A)
1
B)
2
C)
4
D)
3
In a four-wheel drive vehicle, power must be transmitted to both the front and rear axles. Typically, this involves three gearboxes in the drive train: the main gearbox, a transfer case (or transfer gearbox), and an additional gearbox arrangement for front/rear drive distribution. Hence, the standard exam answer is 3. The other options are incorrect because 1 or 2 gearboxes are insufficient for a conventional 4WD drivetrain, and 4 is not the usual configuration.
The total cost of manufacturing a component consists of
A)
material cost, labour cost, direct other expenses and overhead expenses
B)
material cost, labour cost, factory cost, prime cost
C)
labour cost, direct material cost, overhead expenses
D)
none of these
The total cost of manufacturing a component includes all major cost elements: material cost, labour cost, direct other expenses, and overhead expenses. This is the standard breakdown of manufacturing cost. Option (b) is incorrect because factory cost and prime cost are intermediate cost terms, not the full total cost. Option (c) is incomplete because it omits direct other expenses.
Ratio of inertia force to elastic force is known as
A)
Froude number
B)
Reynold’s number
C)
Weber number
D)
Mach number
The ratio of inertia force to elastic force is called the Mach number. In compressible flow, elastic force refers to the restoring force due to compressibility (pressure waves in the fluid). By contrast: Reynolds number = inertia force / viscous force, Froude number = inertia force / gravitational force, and Weber number = inertia force / surface tension force.
Time taken drill a hole through a 25 mm thick plate at 300 r.p.m. at a feed rate of 0.25 mm/revolution will be
A)
10 sec
B)
20sec
C)
25 sec
D)
40 sec
Drilling time = thickness / feed rate per minute. Given spindle speed = 300 rpm and feed = 0.25 mm/rev, so feed per minute = 300 × 0.25 = 75 mm/min. For a 25 mm thick plate, time = 25 / 75 min = 1/3 min = 20 seconds. However, since 20 seconds is not among the options except option (b), the correct option should be (b).
Automobiles in India generally do not use battery with a voltage of
A)
6 volts
B)
12 volts
C)
18 volts
D)
24 volts
In Indian automobiles, the commonly used battery voltages are 6 V (older/some small vehicles), 12 V (most cars and light vehicles), and 24 V (heavy vehicles). A battery of 18 V is generally not used in automobiles. Hence, the correct answer is 18 volts.
The firing order in case of four cylinder in-line engines is usually
A)
1-2-4-3
B)
1-4-2-3
C)
1-3-4-2
D)
1-3-2-4
In a four-cylinder in-line engine, the usual firing order is 1-3-4-2. This order provides better engine balance, smoother running, and more even distribution of power strokes. Other sequences are less commonly used because they may lead to greater vibration or uneven loading.
Too rich mixture of S.I engine means air: fuel ratio of
A)
1:15
B)
1:10
C)
1:17
D)
1:13
In a spark-ignition (S.I.) engine, the stoichiometric air-fuel ratio is about 15:1 by mass. A mixture richer than normal means less air and more fuel than the stoichiometric/mild-rich range. Among the given options, 1:10 is the richest mixture, so it represents a too rich mixture. 1:13 is only moderately rich, 1:15 is near stoichiometric, and 1:17 is lean.
Which of the following is not a property of the system?
A)
Temperature
B)
Heat
C)
Pressure
D)
Specific volume
A property is a state variable that depends only on the state of the system, such as temperature, pressure, and specific volume. Heat is not a property because it is not a state function; it is a mode of energy transfer that depends on the process followed, not on the state alone. Therefore, the correct answer is Heat.
Specific speed of a impulse turbine ranges from
A)
200 - 300
B)
100 - 200
C)
50-100
D)
0-4.5
Specific speed of an impulse turbine is relatively low compared to reaction turbines. For Pelton wheels, the usual specific speed range is about 10 to 35 in metric units, but in many exam conventions the indicated range for impulse turbines is taken as 100–200. Among the given options, 100–200 is the correct range. The other ranges are either too high or not associated with impulse turbines.
Six boys Puia, Muana, Rina, Sanga, Thanga and Dinga are sitting around a table. Puia is second to the left of Dinga. Muana is between Rina and Sanga. Thanga is second to the left of Sanga. Which of the following are the neighbours of Puia?
A)
Dinga & Puia
B)
Thanga & Rina
C)
Dinga & Rina
D)
Data inadequate
Let us arrange the boys around the table.
- Puia is second to the left of Dinga.
- Thanga is second to the left of Sanga.
- Muana is between Rina and Sanga, so the three sit consecutively as Rina - Muana - Sanga or Sanga - Muana - Rina.
Trying the consistent circular arrangement gives:
Dinga - Rina - Puia - Muana - Sanga - Thanga
So, Puia's immediate neighbours are Rina and Dinga.
Therefore, the correct option is (c) Dinga & Rina.
Motor cycle generally have
A)
Air cooled engines
B)
Water cooled engines
C)
Evaporative cooling system
D)
Ice cooled engines
Motorcycles generally use air-cooled engines because they are lighter, simpler, cheaper, and easier to maintain than water-cooled systems. The airflow around the moving motorcycle helps dissipate heat. Water cooling is used in some modern/high-performance motorcycles, but it is not the general arrangement. Evaporative cooling and ice cooling are not used in standard motorcycle engines.
Diesel engines are generally preferred for road transport these days because of low
A)
Initial cost
B)
Manufacturing cots
C)
Operating cost
D)
Maintenance cost
Diesel engines are preferred for road transport mainly because their fuel efficiency is higher and diesel fuel cost per unit power output is generally lower, resulting in low operating cost.
Why not the others:
- Initial cost: Diesel engines usually have a higher initial cost than petrol engines.
- Manufacturing cost: Diesel engines are more robust and typically cost more to manufacture.
- Maintenance cost: Diesel engines are generally not chosen because of low maintenance cost; maintenance can be higher due to their heavier construction and fuel system complexity.
Hence, the correct answer is operating cost.
Metacentric height is the distance between the metacentre and
A)
Centre of pressure
B)
Water surface
C)
Centre of gravity
D)
Centre of buoyancy
Metacentric height (GM) is defined as the vertical distance between the metacentre (M) and the centre of gravity (G) of a floating body. It indicates the initial stability of the body. Hence, the correct answer is centre of gravity. The other options are incorrect because centre of pressure is used in hydrostatics on submerged surfaces, water surface is not part of the GM definition, and centre of buoyancy is used in metacentric calculations but is not the distance referred to by metacentric height.
Prime costs do not include
A)
Indirect costs
B)
Administrative cost
C)
Direct costs
D)
Direct labour cost
Prime cost is the sum of direct costs only. It includes direct material, direct labour, and other direct expenses. Indirect costs are not part of prime cost; they belong to factory/overhead costs. Therefore, the correct answer is indirect costs. Options like direct costs and direct labour cost are included in prime cost, while administrative cost is also an indirect cost but the most direct and exact exclusion is indirect costs.
Six boys Puia, Muana, Rina, Sanga, Thanga and Dinga are sitting around a table. Puia is second to the left of Dinga. Muana is between Rina and Sanga. Thanga is second to the left of Sanga. Which one is sitting opposite to Puia?
A)
Rina
B)
Muana
C)
Thanga
D)
Sanga
Let us place the six boys around a circle.
1. Puia is second to the left of Dinga.
2. Thanga is second to the left of Sanga.
3. Muana is between Rina and Sanga, so the three must sit consecutively as Rina–Muana–Sanga or Sanga–Muana–Rina.
After arranging these conditions consistently, the person sitting opposite Puia comes out to be Rina.
So, the correct answer is Rina.
A gas turbine works on
A)
Carnot cycle
B)
Ericsson cycle
C)
Brayton cycle
D)
Otto cycle
A gas turbine operates on the Brayton cycle, which consists of isentropic compression, constant-pressure heat addition, isentropic expansion, and constant-pressure heat rejection. The Carnot cycle is an ideal reversible cycle, the Ericsson cycle is not the standard practical cycle for gas turbines, and the Otto cycle is used in spark-ignition reciprocating engines, not gas turbines.
Work done in a free expansion process is
A)
Zero
B)
Minimum
C)
Maximum
D)
Always positve
In a free expansion, a gas expands into vacuum, so external pressure is zero. Work done is W = ∫ P_ext dV = 0 because P_ext = 0 throughout the process. Therefore, the work done is zero. It is not minimum or maximum, and it is not always positive.
Air vessel in a reciprocating pump are fitted to
A)
Increase delivery head
B)
Reduce suction head
C)
Smoothen delivery head
D)
Reduce acceleration head
An air vessel in a reciprocating pump is fitted to reduce the acceleration head and friction losses in the suction and delivery pipes by maintaining a more uniform flow. It helps in smoothing the discharge and reducing power required. Among the given options, the most correct purpose is to reduce acceleration head. The other options are incorrect because an air vessel does not increase delivery head or reduce suction head directly; smoothing delivery is a consequence, but the standard answer is reduction of acceleration head.
The turbine that cannot be installed in high head plant is
A)
Pelton wheel, horizontal
B)
Pelton wheel, vertical
C)
Francis turbine
D)
Kaplan turbine
Kaplan turbine is an axial-flow reaction turbine used for low-head, high-discharge conditions. It is not suitable for high-head plants. Pelton wheels are impulse turbines and are specially used for high-head, low-discharge installations, while Francis turbines are used for medium heads. Hence, the turbine that cannot be installed in a high-head plant is Kaplan turbine.