HPCL Mechanical Engineer Mock Test - 10 Free Online Test 2026

The segment is in passive voice, thus only a verb in third form is eligible for the blank. Among all the given options, only ‘discovered’ fits the blank as the virus already existed in the monkeys but was found in 1970.

Hence, option D is correct.

Let us first learn the meanings of the given words:

Span (verb): extend across.

Extend (verb): cause to cover a wider area or make larger.

Vary (verb): differ in size, amount, degree, or nature from something else of the same general class.

Range (verb): extend between specified limits.

The idea here is to express that there was a huge range of reasons why the protests in China had started. Grammatically only a verb in ‘-ing’ form will fit the blank, this eliminates ‘span’, ‘extended’ and ‘vary’. Now, between ‘scoping’ and ‘ranging’, ‘ranging’ is a better option to be placed before ‘from’.

Hence, option d is correct.

The word Meticulous (Adjective) means : paying careful attention to every detail; fastidious; thorough.
Careless in option (c) is the correct autonomy. 

Straw in the wind: something believed to be a sign or warning of a future event.
Shot in the arm: something that has a sudden and positive effect on something, providing encouragement and new activity.
Stroke of luck: a fortunate occurrence that could not have been predicted or expected.
Plain sailing: smooth and easy progress in a process or activity.
Hence, the correct answer is option A. 

Last 20 number = 12th to 31st
So remaining is 11th number.
So the answer = 31 × 57 – 10 × 50 – 20 × 61 = 47
Hence, Option D is correct.

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Visually, the area of the octagonal surface will be the sum of the area of two trapezia and the area of rectangular region.

Area of octagon ABCDEFGH = Area of Trapezium ABCH + Area of rectangle HCDG + Area of trapezium EFGD

Side of the regular octagon = 5 cm

Area of trapezium ABCH = Area of trapezium EFGD

Area of trapezium ABCH = 1/2 × (AB + CH) × AI

= 1/2 × (5 m + 11 m) × 4 m

= 1/2 × 16 m × 4 m

= 32 m²

Area of trapezium ABCH = Area of trapezium EFGD = 32 m²

Area of rectangle HCDG = HC × CD = 11 m × 5 m = 55 m²

Area of ABCDEFGH = Area of trapezium ABCH + Area of rectangle HCDG + Area of trapezium EFGD

= 32 m²+ 55 m²+ 32 m²

= 119 m²

Thus the area of the octagonal surface is 119 m²

Sundays → 2nd, 9th, 16th, 23rd and 30th (5 Sundays)

Hence, Option C is correct.

–12, –6, 0, 6,…
Let a(1) = -12, a(2) = -6, a(3) = 0, a(4) = 6
First relational d,
a(2) – a(1) = -6 – (-12) = 6
Second relational d,
a(3) – a(2) = 0 – (-6) = 6
Third relational d,
a(4) – a(3) = 6 – (0) = 6
all the d are equals to each other, hence
d = 6.

Base =  7 cm
Height  = 4 cm
Area of  Rhombus = Base × Height
= 7 × 4
= 28 cm²

Diameter of the circle = breadth of the rectangle = 42 meters
Radius of the circle

So the answer 

Hence, Option D is correct.

'Jade' is a 'green' precious stone in the same way 'Garnet' is a 'red' precious stone.

1) 8, 4, 6, 1, 5, 3, 7, 2 

2) 7, 8, 3, 4, 5, 2, 6, 1

3) 3, 6, 1, 5, 4, 8, 2, 7

4) 7, 3, 6, 1, 5, 8, 4, 2

'RESIDENT' is a meaningful English word.

Hence, '7, 8, 3, 4, 5, 2, 6, 1' is the correct answer.

The figure shown the no. of triangle is in the diagram so that total no. of triangle is 8 + 8 + 8 + 4 = 28

1st term = 0.5
2nd term = 0.5 + 0.05 = 0.55
3rd term = 0.55 + 0.1 = 0.65
4th term = 0.65 + 0.15 = 0.8

Thus, missing number is 5th term = 0.8 + 0.2 = 1

From the common explanation, we can say that there are at least 16 boys sitting in the row.
Hence, Option B is correct.
Final Arrangement:

Common Explanation:
References:
Only two boys sit to the left of J.
Eight boys sit between R and J.
Only three boys sit between R and M.
Inferences:
From the above references, we get two different cases:

References:
P sits fourth to the right of R.
O sits third to the left of M.
Inferences:
So, from this case 2 will be eliminated as P sits fourth to the right of R.

References:
Only three boys sit between O and H.
T sits third to the right of M.
V sits fourth to the right of O.
More than 12 boys sit between P and H.
More than seven boys sit between P and J.
Inferences:
From the above reference, we get the final arrangement:

As fast mode of 'Walk' is 'Run' in the same way fast mode of 'Breeze' is 'Wind'.

Clearly, the given series consists of prime numbers starting from 2. The prime number after 11 is 13.

Thus, the missing number is 13.

First Law of Thermodynamics:

• Energy can neither be destroyed nor created when it disappears in one form; it must re-appear at the same time in other forms.

• When a closed system executes a complete cycle, the sum of heat interactions is equal to the sum of work interactions.

Second Law of Thermodynamics:

It has two statements:

• Kelvin-Planck Statement: It is impossible to devise a cyclically operating device, the sole effect of which is to absorb energy in the form of heat from a single thermal reservoir and to deliver an equivalent amount of work

• Clausius Statement: It is impossible to devise a cyclically operating device, the sole effect of which is to transfer energy in the form of heat from a low-temperature body to a high-temperature body

Violation of the Kelvin statement implies a violation of the Clausius statement, i.e., the Clausius statement implies the Kelvin statement.

Similarly, the Kelvin statement implies the Clausius statement, and hence the two are equivalent.

A cycloid is a curve traced by a point on the circumference of a circle that rolls without slipping on a fixed straight line.

An involute of a circle is a plane curve generated by a point on a tangent, which rolls on the circle without slipping, or by an end on a taut string that is unwrapped from a reel.

The strain energy stored in a body due to external loading within the elastic limit is known as resilience. The maximum energy that can be stored in a body up to the elastic limit is called proof resilience.

The proof of resilience per unit volume of a material is known as the modulus of resilience.

Strain energy stored in a body due to tensile or compressive load or resilience:

U = σ²V/2E

Modulus of resilience:

U = σ²/2E

So δW = 0

Also, No heat interaction takes place during free expansion. Hence δQ = 0

From the first law of Thermodynamics

δQ = dU + δW

dU = 0

When an object, such as a solid sphere, travels along an axis, that object is usually experiencing both rotational kinetic energy and translation kinetic energy. Therefore the total kinetic energy of the object can be found by summing up the two types of kinetic energy.

Stress-Strain

σ ∝ ϵ

σ = Eϵ

where E is known as Young’s modulus of elasticity.

Since strain (ϵ) is non – dimensional, the unit of E must be the same as those of stress (σ). Thus, E can be expressed in N/mm2, Pa, MPa, GPa, etc.

• Unit of stress: N/mm2 (MPa)

• Unit of strain: Dimensionless

• Unit of Force: N

• Unit of length: mm

Cementite: Cementite or Iron Carbide has the chemical formula Fe3C and contains 6.67% carbon by weight. It is the hardest structure that appears in the iron-carbon equilibrium diagram. Cementite has an orthorhombic crystal structure and is extremely hard and brittle as compared to austenite and ferrite.

Martensite: It is a metastable phase of steel formed by the transformation of austenite below 320°C. Martensite is an interstitial supersaturated solid carbon solution in α – Iron and has a body-centred tetragonal lattice. It has a carbon content of up to 2% and is extremely hard and brittle. It is a product of rapid cooling (quenching) and possesses an acicular or needle-like structure.

The hardness of steel depends upon the amount of cementite. Martensite was obtained after hardening treatment of steel.

Steels with low carbon content do not respond appreciably to hardening treatment because the main constituent is soft ferrite. If hypo-eutectoid steel is cooled rapidly, martensite is formed.

Concept:

Compressor capacity: It is the quantity of air delivered by a compressor in m³/minute or m³/sec

Compression ratio: It is defined as the ratio of the volume of air before compression to the volume of air after compression. It is the ratio of total volume (V₁) to the clearance volume (V_C)

In other words, the compression ratio is the volume of air before compression to the volume of air after compression.

Free air delivery (FAD): The delivery volume reduced in the compressor to a pressure of 1 bar and temperature of 15^∘C. The relative volume at that condition is known as Free Air Delivery.

Swept volume (V_s): The volume displaced or swept by the piston when it moves between the top dead center and bottom dead center.

Clearance volume: The difference between the total volume and the swept volume is the gap that remains between the piston head and the cylinder head when at the top dead center.

As the hot coffee remains hot for a long time so neither heat nor mass is exchanged with the surroundings and hence it is an example of isolated system.

The secondary unbalanced force is maximum, when θ = 0°, 90°,180° and 360°. Thus, the secondary force is a maximum of four times in one revolution of the crank.

• Centrifugal Governor
• Inertia Governor

Centrifugal Governors are classified as:

Dead Weight Governors:

• Porter governor
• Proell governor

Spring controlled governors:

• Hartnell governor
• Hartung governor
• Pickering governor