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Past Questions
“A body, immersed partly or wholly in a fluid at rest, appears to lose a part of its weight, the apparent loss being equal to the weight of the fluid displace” is
A)
Archimedes’ Principle
B)
Pascal’s Law
C)
Newton’s Law of Motion
D)
None of these
The statement describes buoyancy: when a body is partly or wholly immersed in a fluid at rest, it experiences an upthrust equal to the weight of the fluid displaced. This is exactly Archimedes’ Principle. Pascal’s Law deals with transmission of pressure in fluids, and Newton’s laws are general laws of motion, so neither matches this definition.
An engine has a clearance volume of 100cm³ and swept volume of 800cm³. The compression ratio is
A)
7:1
B)
9:1
C)
10:1
D)
8:1
Compression ratio = (Swept volume + Clearance volume) / Clearance volume = (800 + 100) / 100 = 900 / 100 = 9. So the compression ratio is 9:1. Therefore, the correct option is (b), not (d).
The octane rating of petrol commercially available is usually
A)
85-90
B)
90 - 100
C)
100-110
D)
110 - 125
The octane rating of commercially available petrol is usually in the range of about 85 to 90. This is the commonly used fuel grade range for petrol in standard engineering exam context. Options (b), (c), and (d) are too high and correspond to special high-octane or racing-type fuels, not ordinary commercial petrol.
The firing order in case of four cylinder in-line engine is usually
A)
1-2-4-3
B)
1-3-4-2
C)
1-4-3-2
D)
Either (b) or (c)
In a four-cylinder in-line engine, the usual firing orders are 1-3-4-2 or 1-4-3-2, depending on the engine design and crank arrangement. Both are commonly used to obtain better balance and smooth running. Therefore, the correct choice is 'Either (b) or (c)'. Options (a) 1-2-4-3 is not the usual firing order for a four-cylinder in-line engine.
A process, which can be reversed bringing both the state of the system and the surroundings to the initial condition without any other inputs is
A)
Irreversible process
B)
Reversible process
C)
Constant process
D)
None of these
A reversible process is one that can be reversed so that both the system and the surroundings return exactly to their initial states without any net change. This matches the definition given in the question. An irreversible process cannot be exactly reversed. 'Constant process' is not a standard thermodynamic classification here.
A four-cylinder engine has a capacity of 2.4 litres. The swept volume of one cylinder is
A)
2400 cm³
B)
600 cm³
C)
1200 cm³
D)
400 cm³
The total engine capacity is 2.4 litres = 2400 cm³. For a four-cylinder engine, swept volume per cylinder = 2400 ÷ 4 = 600 cm³. Hence, option (b) is correct. The other options are incorrect because they do not equal one-fourth of the total capacity.
Which part is not common between the SI engine and CI engines?
A)
Fuel Injector
B)
Air Cleaner
C)
Battery
D)
Exhaust Silencer
In an SI (spark ignition) engine, fuel is generally supplied by a carburettor or fuel injection system, while in a CI (compression ignition) engine a fuel injector is essential to inject fuel directly into the cylinder at high pressure. Air cleaner and exhaust silencer are common parts in both engines, and battery is also commonly used in starting/ignition systems. Therefore, the part not common between SI and CI engines is the fuel injector.
In a centrifugal pump installation, while starting the position of delivery valve is
A)
Fully closed
B)
Fully open
C)
Half open
D)
More than half open
In a centrifugal pump, the delivery valve is kept fully closed while starting. This reduces the load on the motor at start-up because the pump initially develops head but has not yet built up sufficient discharge. After the pump attains normal speed, the delivery valve is opened gradually. If it were open at starting, the motor could be overloaded.
A type of pump, where a nozzle is placed at the throat of a venturi tube and it discharges either compressed air or steam or water at high velocity. The jet causes suction and water is drawn from suction pipe. The high velocity of mixture is converted into pressure head and the water is raised in the discharge pipe, is known as
A)
Hydraulic ram
B)
Jet Pump
C)
Rotary Pump
D)
None of these
The description matches a **jet pump** (also called an ejector or injector in some contexts). In this pump, a nozzle at the throat of a Venturi tube ejects a high-velocity jet of compressed air, steam, or water. This creates suction that draws water from the suction pipe, and the momentum of the jet-mixed fluid is then converted into pressure head in the discharge pipe.
- **Hydraulic ram** uses the water hammer effect to lift water, so it does not fit.
- **Rotary pump** is a different positive displacement pump type and does not work by jet-induced suction.
- Therefore, the correct answer is **Jet Pump**.
Refrigerant usually used in refrigeration in aeroplane
A)
CO₂
B)
Air
C)
Freon
D)
None of these
In aircraft refrigeration systems, air is usually used as the refrigerant because it is readily available, light in weight, and safe for use in aeroplanes. This is the basis of the air-cycle refrigeration system commonly employed in aircraft. CO₂ and Freon are not the usual refrigerants for aeroplane refrigeration in standard exam context.
The type of engine used in heavy commercial Vehicle is
A)
External Combustion
B)
Petrol
C)
Diesel
D)
Spark ignition
Heavy commercial vehicles generally use diesel engines because they produce higher torque at low speeds, are more fuel-efficient, and are better suited for heavy loads. Petrol and spark ignition engines are lighter-vehicle engines, and external combustion engines are not used in commercial road vehicles.
IC engine includes
A)
Diesel engine
B)
Petrol engine
C)
Spark Ignition engine
D)
Any of these
IC stands for Internal Combustion engine. Diesel engine and petrol engine are both internal combustion engines. Also, petrol engines are spark-ignition (SI) engines. Since all the listed engines fall under IC engines, the correct option is 'Any of these'.
One effect of a punctured carburettor float is
A)
Weak mixture
B)
Low petrol level
C)
High air fuel mixture
D)
Petrol flooding
A carburettor float controls the fuel level in the float chamber. If the float gets punctured, it fills with petrol, loses buoyancy, and cannot close the needle valve properly. This causes excess petrol to enter the carburettor, leading to flooding. Hence, the correct effect is petrol flooding. The other options are incorrect because a punctured float does not lower the petrol level or make the mixture weak; it does the opposite by allowing too much fuel.
At the first sight a petrol engine is identified by
A)
Cylinder size
B)
Power output
C)
Operating speed
D)
Spark plug
A petrol engine is a spark-ignition engine, so its most distinctive visible feature is the spark plug used to ignite the air-fuel mixture. Diesel engines, in contrast, do not use spark plugs; they use compression ignition. Cylinder size, power output, and operating speed are not unique identifiers of a petrol engine.
A single cylinder, 4 - stroke engine is rotating at 1000 rpm. The number of power strokes occurring in one minute is
A)
500
B)
1000
C)
1500
D)
2000
In a 4-stroke engine, one power stroke occurs after every 2 revolutions of the crankshaft. At 1000 rpm, the engine makes 1000 revolutions per minute, so the number of power strokes per minute = 1000/2 = 500. Hence, option (a) is correct. The other options do not match the 2-revolutions-per-power-stroke rule for a single-cylinder 4-stroke engine.
Control of temperature, humidity, purity and motion of air in an enclosed space, independent of outside conditions is known as
A)
Air-conditioning
B)
Air- circulating
C)
Flow- controlling
D)
None of these
Air-conditioning is the process of controlling temperature, humidity, purity, and motion of air in an enclosed space so that comfort or required conditions are maintained regardless of outside weather. The other options do not describe this full environmental control.
The mechanical device or arrangement by which water is caused to flow at increased pressure (higher level) is known as
A)
Electric Motor
B)
A pump
C)
Blower
D)
None of these
A pump is a mechanical device used to raise water or other fluids from a lower level to a higher level, increasing the pressure and causing flow. An electric motor only supplies mechanical power, while a blower is used for moving air or gas, not water. Hence, the correct answer is A pump.
Which one is not the method of cooling an I.C. engine?
A)
Air cooling
B)
Oil cooling
C)
Water cooling
D)
Steam cooling
The common methods of cooling an I.C. engine are air cooling, water cooling, and sometimes oil cooling. Steam cooling is not used as a standard cooling method in I.C. engines. Therefore, the correct answer is Steam cooling.
Which type of turbine is different from the others?
A)
Pelton turbine
B)
Propeller turbine
C)
Kaplan turbine
D)
Francis turbine
Pelton turbine is different from the others because it is an impulse turbine, while Propeller, Kaplan, and Francis turbines are reaction turbines. In a Pelton turbine, the entire pressure drop occurs in the nozzle before the water strikes the buckets. In the other three, water acts under pressure within the runner, so they belong to the reaction type.
Automobile gears are generally made of
A)
Brass
B)
Alloy steel
C)
Stainless steel
D)
Mild steel
Automobile gears are generally made of alloy steel because it offers high strength, toughness, wear resistance, and can be heat-treated to improve surface hardness. Brass is too soft, stainless steel is not commonly used for gears due to cost and lower wear suitability, and mild steel lacks the required hardness and durability for gear teeth under heavy load.
Which one is not components of cost?
A)
Prime cost
B)
Factory cost & Office cost
C)
Total cost
D)
None of these
In cost accounting, the main components of cost include prime cost, factory/works cost, office/administration cost, and total cost. Since options (a), (b), and (c) are all recognized cost elements or cost stages, none of them is ‘not a component of cost’. Therefore, the correct answer is (d) None of these.
The amount (percentage) of water in the air is known as
A)
Density
B)
Specific gravity
C)
Humidity
D)
None of these
The amount of water vapor present in air is called humidity. Density refers to mass per unit volume, and specific gravity is the ratio of the density of a substance to that of water. Therefore, the correct answer is humidity.
Which one is not the part of gas turbine?
A)
Compressor
B)
Regenerator
C)
Combustion Chamber
D)
Piston
A gas turbine consists of a compressor, combustion chamber, and turbine; a regenerator may also be used in some cycles to improve efficiency. A piston is a component of reciprocating engines, not gas turbines. Therefore, the correct answer is Piston.
The principle of a radiator of an engine cooling system is to
A)
Act as a reservoir for the water
B)
Cause heat flow by convection currents
C)
Spread out the hot water over a large area
D)
Increase the air speed as it flows over the hot surface
A radiator cools engine water/coolant by exposing it to a large surface area, so heat can be rejected quickly to the surrounding air. The hot water flows through thin tubes and fins, which spread the heat over a large area. (a) is not the main principle, (b) is too vague and refers to air circulation rather than the radiator’s basic design, and (d) describes the fan/airflow effect, not the radiator principle itself.
In a four-stroke engine, each cylinder has
A)
One valve
B)
Two valves
C)
Three valves
D)
Four valves
In a basic four-stroke engine, each cylinder is generally provided with two valves: one inlet (intake) valve and one exhaust valve. The inlet valve allows the air-fuel mixture or air to enter, and the exhaust valve lets the burnt gases leave. Hence, the correct answer is two valves. The other options are not the standard arrangement for a basic four-stroke engine.