HPCL Mechanical Engineer Mock Test - 4 Free Online Test 2026

Clandestine means kept secret or done secretively, especially because illicit

The clandestine meeting took place in his house in the dead of night
The retailers also engaged in clandestine hoarding of pulses to artificially increase its price

for a given AP, the Nth term is:
a(n) = a + (n-1) x d
a(17) = a + (17−1) x d
a(17) = a + 16 x d
a(10) = a+9(d)
a(17) – a(10) = 7
(a + 16 x d) − (a + 9 x d) = 7
7 x d = 7
d = 1

Side of the square = √144 = 12 cm

So the answer = π × 3 × 3 = 9π cm² 

Chalk box and soap have breadth,length and height . Cylinder has 2 radii and height. A ring (here) is made up of two concentric circles which is a 2d figure. Hence ring is 2 dimensional

Definition of Area : The space enclosed by the boundary of a plane figure.
Surface area: It is same as area in simple we can say that the amount of space enclosed by the surface.
Voume : It is defined as the amount of Space occupied by any three dimensional object.
Lateral surface area: it is defined as the space enclosed by any lateral surfaces.
So the option C is correct

First Number x Second Number = HCF x LCM
Then, 75 x Second Number = 15 x 225
Second Number latex ={ 15 x 225}/75 = 45$
Therefore, other number is 45. 

Given number: 7 8 3 4 3 2 9 5 1 3

After interchanging the digits,
New number: 8 7 4 3 2 3 5 9 3 1

6th digit from right end

According to question,
A's weight is twice as much as of B.
1. A = 2B.
B's weight is four and half times as much as of C.
2. B = 4.5C
C's weight is half times as much as of D.
3. C = D/2.
D's weight is half as much as of E.
4. D = E/2.
E weight is less than A but more than C.
5. A > E > C
from 1 and 2
6. A = 2B = 9C
from 6 and 3
7. A = 2B = 9C = 4.5D
from 7 and 4
8. A = 2B = 9C = 4.5D = 2.25E
so from 8 and 5
A > B > E > D > C
So, E is lighter in weight than A and B.

As Microphone makes sound louder similarly Microscope makes the object magnified.

Mayer’s Equation for an ideal gas:

C_p – C_v = R

The ratio of Specific heat is known as an adiabatic index.

γ = C_p/C_v

Calculation:

C_p = 7/2R

C_v = C_p − R = 7/2R − R = 5/2R

γ = C_p/C_v = 7/5 = 1.4

In eutectoid reaction, the austenite transforms into a phase mixture of ferrite (containing 0.76% C) and cementite. This phase mixture is known as pearlite. The eutectoid reaction occurs at a constant temperature. This is known as eutectoid temperature and is 723^oC

A spark-ignition engine (SI engine) is an internal combustion engine, generally a petrol engine. The combustion process of the air-fuel mixture is ignited by a spark from a spark plug.

P + 1/2ρV² + ρgh = c

P is the pressure, r is the density, v is the velocity, h is the elevation difference.

The value of C in the above equation is constant only along a streamline and should essentially vary from streamline to streamline.

The equation can be used to define the relation between flow variables at point B on the streamline and at point A, along the same streamline. So, to apply this equation, one should have knowledge of the velocity field beforehand. This is one of the limitations of the application of Bernoulli's equation.

Therefore, the total mechanical energy remains constant everywhere in inviscid and irrotational flow, while it is constant only along a streamline for inviscid but rotational flow.

Where ∂P/∂x = pressure gradient along the length of the plate

y = point of consideration from the lower fixed plate

t = distance between the two fixed parallel plates

Velocity distribution and Shear stress distribution

Physical Properties of Refrigerants

Low Condensing Pressure.
High Evaporator Pressure.
High Critical Pressure.
High Vapor Density.
High Dielectric strength.
High Latent Heat of Vaporization.
High Heat Transfer Coefficient.

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. Protons and neutrons are bound together to form a nucleus by the nuclear force.

The epicyclic gear trains are useful for transmitting high-velocity ratios with gears of moderate size in a comparatively lesser space. The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wristwatches, etc.

Q_{supplied = 60KJ}

_{du= -30 KJ}

_{from first law of thermo=}

_{dQ = du + dW}

_{60 = -30 + dW}

_{dW = 90 KJ}

p = ρgh

Pressure distribution profile

dp/dz = -ω = -pg

dp = -ω.dz

It indicates that a negative pressure gradient exists upward along any vertical.

Thus, the pressure decreases in the upward direction and increases in the downward direction with a magnitude equal to a specific weight.

In 1909, Robert Millikan and Harvey Fletcher conducted the oil-drop experiment to determine the charge of an electron. Using the known electric field and the values of gravity and mass, Millikan and Fletcher determined the charge on oil droplets in mechanical equilibrium.

• Stable equilibrium : GM > 0 (M is above G)
• Neutral equilibrium : GM = 0 (M coinciding with G)
• Unstable equilibrium : GM < 0="" (m="" is="" below="" g)="">

(a) Equilibrium Position (b)Tilted Position

Condition of stable equilibrium for a floating body in terms of centre of buoyancy and the centre of gravity:

• Stable equilibrium: If its centre of gravity is directly below the centre of buoyancy
• Neutral equilibrium: If its centre of gravity is coincident with the centre of buoyancy
• Unstable equilibrium: If its centre of gravity is directly above the centre of buoyancy

A submerged body is in equilibrium when the centre of gravity is located below the centre of buoyancy. If the body is tilted slightly in any direction, the buoyant force and the weight always produce a restoring couple trying to return the body to its original position.

Strain Energy of the member is defined as the internal work done in deforming the body by the action of externally applied forces.

Resilience is defined as the capacity of a strained body for doing work on the removal of the straining force.

Proof resilience is defined as the maximum strain energy stored in a body. So, it is the quantity of strain energy stored in a body when strained up to the elastic limit (ability to store or absorb energy without permanent deformation).

Modulus of resilience is defined as proof resilience per unit volume. It is the area under the stress-strain curve up to the elastic limit.

The modulus of toughness is the ability to absorb energy up to fracture. From the stress-strain diagram, the area under the complete curve gives the measure of modulus of toughness.

If the speed is kept constant, the variation of manometric head, power, and efficiency with respect to discharge gives the operating characteristic curves of a pump.

Some familiar properties are pressure, temperature, volume, and mass.

Properties may be divided into two categories, i.e., extensive (dependent of mass) and intensive (independent of mass) properties.

It is used in calculating the heat transfer, typically by convection or phase transition between a fluid and a solid. The heat transfer coefficient has SI units in watts per squared meter kelvin: W/(m²K). The heat transfer coefficient is the reciprocal of thermal insulance.