GPSC Assistant Engineer 2023: Preliminary, Assistant Engineer (Mechanical) Class-2 (GWSSB) (Series BEX)
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BEX(CBRT)
PROVISIONAL ANSWER KEY
Name of the post Assistant Engineer (Mechanical), Class-2 (GWSSB)
Advertisement No. 26/2023-24
Preliminary Test held 18-08-2023
Question No. 01-300
19-08-2023
Publish Date
Last Date to Send Suggestion(s) 24-08-2023
THE LINK FOR ONLINE OBJECTION SYSTEM WILL START FROM 20-08-2023; 04:00 PM ONWARDS
Instructions / ૂચના
Candidate must ensure compliance to the instructions mentioned below, else objections
shall not be considered: -
(1) All the suggestion should be submitted through ONLINE OBJECTION SUBMISSION SYSTEM only.
Physical or submission through E- Mail of suggestions will not be considered.
(2) Question wise suggestion to be submitted in the prescribed format (proforma) published on the
website / online objection submission system.
(3) All suggestions are to be submitted with reference to the Master Question Paper with provisional
answer key (Master Question Paper), published herewith on the website / online objection
submission system. Objections should be sent referring to the Question, Question No. & options of
the Master Question Paper.
(4) Suggestions regarding question nos. and options other than provisional answer key (Master
Question Paper) shall not be considered.
(5) Objections and answers suggested by the candidate should be in compliance with the responses given
by him in his answer sheet. Objections shall not be considered, in case, if responses given in the answer
sheet /response sheet and submitted suggestions are differed.
(6) Objection for each question should be made on separate sheet. Objection for more than one question
in single sheet shall not be considered.
ઉમેદવાર નીચેની ૂચનાઓ ુ ં પાલન કરવાની તકદાર રાખવી, અ યથા વાંધા- ૂચન ગે કરલ ર ૂ આતો યાને લેવાશે નહ
(1) ઉમેદવાર વાંધાં- ૂચનો ફ ત ઓનલાઈન ઓ શન સબમીશન સી ટમ ારા જ સબમીટ કરવાના રહશે. બ અથવા ટપાલ
અથવા ઇ- મેઇલ ારા આયોગની કચેર એ મોકલવા આવેલ વાંધા- ૂચનો યાને લેવામા આવશે નહ ની ખાસ ન ધ
લેવી.
(2) ઉમેદવાર વાંધા- ૂચનો ર ૂ કરવા વેબસાઈટ / ઓનલાઈન ઓ શન સબમીશન સી ટમ પર િસ ધ થયેલ િનયત
ન ૂનાનો જ ઉપયોગ કરવો.
(3) ઉમેદવાર પોતાને પર ામાં મળેલ પ ુ તકામાં છપાયેલ માક ુજબ વાંધા- ૂચનો ર ૂ ન કરતા તમામ
વાંધા- ૂચનો વેબસાઈટ પર િસ ધ થયેલ ોિવઝનલ આ સર ક (મા ટર પ )ના માંક ુજબ અને તે સંદભમાં
ર ૂ કરવા.
(4) મા ટર પ માં િન દ ટ અને િવક પ િસવાયના વાંધા- ૂચનો યાને લેવામાં આવશે નહ .
(5) ઉમેદવાર ના િવક પ પર વાંધો ર ૂ કરલ છે અને િવક પ પે જવાબ ૂચવેલ છે એ જવાબ ઉમેદવાર પોતાની
ઉ રવહ માં આપેલ હોવો જોઈએ. ઉમેદવાર ૂચવેલ જવાબ અને ઉ રવહ નો જવાબ ભ હશે તો ઉમેદવાર ર ૂ કરલ
વાંધા- ૂચનો યાનમા લેવાશે નહ .
(6) એક માટ એક જ વાંધા- ૂચન પ ક વાપર ું. એક જ વાંધા- ૂચનો પ કમાં એકથી વધાર ોની ર ૂઆત કરલ હશે તો
તે ગેના વાંધા- ૂચનો યાને લેવાશે નહ .
Website link for online objection submission system : http://gpsc.safevaults.in/login/
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101. Amount of energy required to raise the temperature of a substance of 1 kg mass by 1°C is
called
(A) Specific entropy (B) Specific heat capacity
(C) Sensible heat (D) Latent heat
102. If a heat engine produces work only by interacting with one source. What kind of machine is
this?
(A) PMM1 (B) PMM2
(C) PMM3 (D) None of the above
103. In a cyclic process, the change in internal energy of the system is
(A) Positive (B) Negative
(C) Zero (D) Cannot be determined.
104. If temperature of the source is increased, the efficiency of Carnot engine
(A) Increases
(B) Degreases
(C) Remains Constant
(D) First increases and then becomes constant
105. A thermodynamic process where no heat is exchanged with the surroundings is
(A) isothermal (B) adiabatic
(C) isobaric (D) isotropic
106. An adiabatic boundary is one which
(A) prevents heat transfer (B) permits heat transfer
(C) prevents work transfer (D) permits work transfer
107. Ice kept in a wall insulated thermo-flask is an example of which system?
(A) closed system (B) isolated system
(C) open system (D) non-flow adiabatic system
108. Consider the following:
1. Temperature
2. Viscosity
3. Specific entropy
4. Thermal conductivity
Which of the above properties of a system is /are intensive?
(A) 1 only (B) 2 and 3 only
(C) 2, 3 and 4 only (D) 1, 2, 3 and 4
109. A closed system receives 60 kJ heat but its internal energy decreases by 30 kJ. Then the work
done by the system is
(A) 90 kJ (B) -30 kJ
(C) 30 kJ (D) -90 kJ
110. The cyclic integral of (δQ- δw ) for a process is
(A) Positive (B) Negative
(C) Zero (D) Unpredictable
111. The first law of thermodynamics is the law of
(A) Conservation of mass (B) Conservation of energy
(C) Conservation of momentum (D) Conservation of temperature
BEX – MASTER ] 1 [ Contd…
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112. Given that along the path 1-2-3 a system absorbs 100 kJ as heat and does 60 kJ work while
along the path 1-4-3 it does 20 kJ work (see figure given). The heat absorbed during the cycle
1-4-3 is
(A) 140 kJ (B) - 80 kJ
(C) - 40 kJ (D) 60 kJ
2
113. A composite wall of surface area 1 m has three layers of thickness 0.3 m, 0.2 m, and 0.1 m
and has thermal conductivities 0.6, 0.4, and 0.1 W/m°C, respectively. There is no generation
of thermal energy within the wall. If the inner and outer temperatures of the composite wall
are 1840°C and 340°C, respectively, the rate of heat transfer through this wall is:
(A) 0.75 kW (B) 0.150 kW
(C) 7.5 kW (D) 1.5 kW
114. The critical radius of insulation for asbestos with thermal conductivity, k=0.17 W/m°C
surrounding a pipe and exposed to a room air at 25°C with heat transfer coefficient h = 4.0
W/m2 °C will be _______.
(A) 4.25 cm (B) 5.8 cm
(C) 7 cm (D) 8.3
115. A metallic rod 15 mm diameter at 90°C is cooled to 30°C in 105 seconds by placing in air
stream at 25°C. The heat transfer coefficient ‘h’ for air is _______.
[For the rod mass of 1kg, Cp = 350 J/kg, surface area= 0.0004 m2]
(A) 213 W (B) 413 W
(C) 426 W (D) 326 W
116. With an increase in thickness of insulation around a circular pipe, heat loss to the
surrounding due to _______.
(A) Convection increases, while that due to conduction decreases
(B) Convection decreases, while that due to conduction increases
(C) Convection and conduction decreases
(D) Convection and conduction increases
117. Biot number signifies the ratio of
(A) Convection resistance in the fluid to conductive resistance in the solid
(B) Conductive resistance in the solid to convective resistance in the fluid
(C) Inertia force to viscous force in the fluid
(D) Buoyancy force to viscous force in the fluid
118. At thermal equilibrium
(A) Absorptivity is greater than emissivity
(B) Absorptivity is less than emissivity
(C) Absorptivity is equal to emissivity
(D) Sum of absorptivity and emissivity is unity
BEX – MASTER ] 2 [ Contd…
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119. Air at 25°C flows over a thin plate with a velocity of 2.5 m/s. The plate is 2 m long and 1 m
wide. At 25°C, the density of the air is 1.2 kg/m3 and kinematic viscosity is 15 x 10-6 m2/s,
Prandtl number of air = 0.69. The thermal boundary layer at the trailing edge of the plate
along the length is ______
(A) 2.5 cm (B) 3.2 cm
(C) 2.1 cm (D) 1.96 cm
120. The drag and lift forces experienced by an object placed in a fluid stream are due to
(A) Pressure and turbulence (B) Viscosity and turbulence
(C) Pressure and viscosity (D) Pressure and gravity
121. What is the surface temperature of the outlet of the tube where local convection coefficient
at the tube outlet is 48.7 W/m2K?
(A) 121.06°C (B) 101.06°C
(C) 81.06°C (D) 61.06°C
122. For laminar forced convection over a flat plate, if the free stream velocity increases by a
factor of 2, the average heat transfer coefficient_______
(A) Remains same (B) Decreases by a factor of under root 2
(C) Rises by a factor of under root 2 (D) Rises by a factor of 4
123. Thermal radiations are electromagnetic radiations whose wavelength vary.
(A) Between 0.1 to 100 μm (B) Between 0.4 to 0.76 μm
(C) Between 100 μm to 10 μm8
(D) Between 150 μm to 105 μm
124. Two long parallel plates of same emissivity 0.5 are maintained at different temperatures and
have radiation heat exchange between them. The radiation shield of emissivity 0.25 place in
middle will reduce heat exchange to:
(A) 1/2 (B) 1/4
(C) 3/10 (D) 3/5
125. What is the maximum possible effectiveness of the arrangement of heat exchanger in counter
flow:
(A) 4 (B) 3
(C) 2 (D) 1
126. ‘Fouling factor’ is used in heat exchanger design for:
(A) Compensating the directional changes in the fluid flow
(B) Compensating for the loss of heat exchange due to scale formations
(C) Compensating for the heat loss due to friction within tubes
(D) Compensating for the coolant contamination
127. In a heat exchanger, it is observed that ∆T1=∆T2, where ∆T1 is the temperature difference
between the two single phase fluid streams at one end and ∆T2 is the temperature difference
at the other end. This heat exchanger is
(A) A condenserb (B) An evaporator
(C) A counter flow heat exchanger (D) A parallel floe heat exchanger
128. A 2 kW electric resistance heater submerged in 5 kg water is turned on and kept on for 10
min. During the process 300 kJ of heat is lost from the water the temperature rise of water is
(A) 57.4°C (B) 43.1°C
(C) 71.8°C (D) 180°C
BEX – MASTER ] 3 [ Contd…
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129. In a Carnot engine, when the working substance gives heat to the sink
(A) the temperature of the sink increases
(B) the temperature of the sink remains the same
(C) the temperature of the source decreases
(D) the temperatures of both the sink and the source decrease
130. Newton’s law of viscosity depends upon the
(A) stress and strain in a fluid (B) shear stress, pressure, and velocity
(C) shear stress and rate of strain (D) viscosity and shear stress
131. Which of the following forces act on a fluid at rest?
1. Gravity force
2. Hydrostatic force
3. Surface tension
4. Viscous force
Select the correct option from the given choices.
(A) 1, 2, 3 and 4 (B) 1, 2 and 3
(C) 1, 3 and 4 (D) 1 and 2
132. Surface tension is due to
(A) viscous forces
(B) cohesion
(C) adhesion
(D) the difference between adhesive and cohesive forces
133. Work done in a free expansion process is
(A) zero (B) minimum
(C) maximum (D) positive
134. With an increase in the thickness of insulation around a circular pipe, heat loss to the
surrounding due to ____.
(A) Convection and conduction decreases
(B) Convection decreases while that due to conduction increases
(C) Convection increases while that due to conduction decreases.
(D) Convection and conduction increases.
135. The formation of vapour and air pockets in liquid results in phenomenon called:
(A) Erosion (B) Cavitation
(C) Turbulence (D) Whirling
136. The velocity distribution in a laminar boundary layer is:
(A) Parabolic (B) Cubic
(C) Linear (D) Random
137. What are the dimensions of kinematic viscosity of a fluid?
(A) LT-2 (B) ML-1T -1
2 -1
(C) L T (D) ML-2T -2
138. A 150 mm diameter shaft rotates at 1500 rpm within a 200 mm long journal bearing with
150.5 mm internal diameter. The uniform annular space between the shaft and the bearing
is filled with oil of dynamic viscosity 0.8 poise. The shear stress on the shaft will be:
(A) 1.77 kN/m2 (B) 2.77 kN/m2
2
(C) 3.77 kN/m (D) 4.77 kN/m2
BEX – MASTER ] 4 [ Contd…
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139. The Pelton wheel is a/an _______ impulse turbine.
(A) axial flow (B) mixed flow
(C) radial flow (D) tangential flow
140. In the stability of floating bodies, stable equilibrium is attained if the meta centre (M) point
the centre of gravity (G).
(A) lies above (B) coincides with
(C) is parallel to (D) lies below
141. A vertical triangular plane area, submerged in water, with one side in the free surface, vertex
downward and latitude ‘h’ was the pressure centre below the free surface by
(A) h/4 (B) h/3
(C) 2h/3 (D) h/2
142. Water flows at a steady velocity through a horizontal pipe with a changeable diameter. The
water velocity is 2 m/sec, and the pressure is 2.5 kPa at point A. The pressure drops to 1.5
kPa at point B. What is the water velocity at point B?
(A) 6 m/sec (B) 6 m/sec
(C) 3 m/sec (D) 3 m/sec
143. Which of the following is the cheapest plant in operation and maintenance?
(A) Thermal power plant (B) Nuclear power plant
(C) Hydropower plant (D) All of the mentioned
144. Which of the following is also known as Coal used in power plant?
(A) Coke (B) Soft coal
(C) Charcoal (D) Steam coal
145. The steam from steam generator of a nuclear power plant is best described as
(A) saturated dry steam (B) saturated wet steam
(C) supercritical steam (D) superheated steam
146. The gas turbine power plant mainly uses which among the following fuels?
(A) Kerosene oil and diesel oil and residual oil
(B) Natural gas and liquid petroleum fuel
(C) Coal and Peat
(D) Gas oil
147. What is the purpose of using open heaters in steam power plants?
(A) feedwater deaeration (B) feedwater carbonisation
(C) feedwater esterification (D) feedwater purification
148. Compounding of steam turbine is done for
(A) reducing the work done (B) increasing the rotor speed
(C) reducing the rotor speed (D) balancing the turbine
149. Rankine cycle efficiency of a good steam power plant is in the range of
(A) 15 to 20 percent (B) 35 to 45 percent
(C) 70 to 80 percent (D) 90 to 95 percent
150. Economiser is used to heat
(A) Air (B) Feed water
(C) Flue gases (D) All of the above
151. Artificial draught is produced by
(A) Induced fan (B) Forced fan
(C) Induced and forced fan (D) All of the above
BEX – MASTER ] 5 [ Contd…
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152. What is the difference between a Rankine cycle & a Brayton cycle?
(A) working fluid in a Brayton cycle undergoes phase change while it doesn’t in Rankine
cycle
(B) working fluid in a Brayton cycle doesn’t undergo phase change while it does in Rankine
cycle
(C) both are same
(D) none of the mentioned
153. Which type of compressor is used in a gas turbine plant?
(A) Reciprocating compressor
(B) Screw compressor
(C) Multistage axial flow compressor
(D) Either Reciprocating compressor & Screw compressor
154. The surge tanks are usually provided in high or medium head _______ power plants when
considerably _______ is required.
(A) Hydro-electric, short penstock (B) Hydro-electric, long penstock
(C) Thermal, short penstock (D) Thermal, Large steam turbine
155. In thermal power plants, the function of economizer is to:
(A) Heat steam from boiler (B) Heat feed water using flue gas
(C) Heat air fuel mixture (D) Heat steam taken from turbine outlets
156. Evaporative type of condenser has
(A) Steam in pipes surrounded by water (B) Water in pipes surrounded by steam
(C) Either (A) or (B) (D) None of the above
157. The average ash content in Indian CO is about
(A) 5% (B) 10%
(C) 15% (D) 20%
158. An I.C engine works with a compression ratio of 16. If cut-off happens at 8% of the stroke,
then the cut-off ratio of this engine is:
(A) 1.2 (B) 2.2
(C) 4.2 (D) 3.2
159. A 4-stroke 4-cylinder reciprocating engine has cylinder diameter of 4 cm, stroke length of 7
cm and clearance volume 2 cm3. The engine capacity in cc is:
(A) 110 (B) 252
(C) 400 (D) 352
160. If the cut-off ratio in the air standard dual cycle approaches unity, then this lead to which
among the following cycles?
(A) Diesel cycle (B) Brayton cycle
(C) Rankine cycle (D) Otto cycle
161. Combustion that takes place at high speed is called_______.
(A) Spontaneous burning (B) Explosion
(C) Incomplete burning (D) Rapid combustion
162. An air standard cycle which consists of two isothermal and two constant volume processes:
(A) Lenoir cycle (B) Stirling cycle
(C) Diesel cycle (D) Otto cycle
BEX – MASTER ] 6 [ Contd…
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163. For same maximum and minimum temperatures, the Rankine cycle has:
(A) more efficiency than that of the Carnot cycle
(B) equal efficiency to that of the Carnot cycle
(C) lower specific work output than that of the Carnot cycle
(D) higher specific work output than that of the Carnot cycle
164. If dry saturated steam is admitted to a steam turbine following an isentropic process, at the
exit of the turbine, it will be a:
(A) Superheated steam (B) Dry saturated steam
(C) Liquid condensate (D) Wet steam
165. Mechanical efficiency of a certain engine is 75% and it develops a brake power of 40 kW.
What will be the new mechanical efficiency at half load if friction power is assumed to be
constant?
(A) 65% (B) 40%
(C) 60% (D) 58%
166. Which one of the following is NOT a necessary assumption for the air-standard Otto cycle ?
(A) All processes are both internally as well as externally reversible.
(B) Intake and exhaust processes are constant volume heat rejection processes.
(C) The combustion process is a constant volume heat addition process.
(D) The working fluid is an ideal gas with constant specific heats.
167. The compression ratio for petrol engines is
(A) 3 to 6 (B) 5 to 8
(C) 15 to 20 (D) 20 to 30
168. The Otto cycle is an air standard cycle of spark ignition engine. The sequence of first four
processes of the engine is
(A) Intake, Expansion, Combustion, Compression
(B) Intake, Combustion, Compression, Expansion
(C) Intake, Compression, Combustion, Expansion
(D) Intake, Combustion, Expansion, Compression
169. An otto cycle has maximum temperature of heat addition at 1200 K and exhaust temperature
of 600 K? At beginning of compression, the pressure and temperature of air is 1 Bar and
27°C. Find out the compression ratio of air. Assume γ for air is 1.4
(A) 3.65 (B) 5.65
(C) 4.66 (D) 8.65
170. An air-standard diesel cycle consists of
(A) two adiabatic and two constant volume processes
(B) two constant volume and two isothermal processes
(C) one constant pressure, one constant volume and two adiabatic processes
(D) one constant pressure, one constant volume and two isothermal processes
171. Air lock in fuel line will cause
(A) Engine idling high (B) Injector pressure is too high
(C) Late starting and erratic running (D) Excess delivery from FI pump
172. Which of the following is the standard format for recording defects in a vehicle at a service
station?
(A) Job card (B) Vehicle manual
(C) Log book (D) Maintenance manual
BEX – MASTER ] 7 [ Contd…
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173. Which one of the following is suitable reason for engine overheat?
(A) Clogged radiator core (B) Low idle speed setting
(C) Excessive valve clearance (D) Too high viscosity of oil
174. In engine, the customer reported as engine gets overheated, the mechanic should check for
the problem is most likely caused by a
(A) excessive tappet clearance (B) defective pressure relief valve
(C) Worn out piston/liner/rings (D) loose fan belt
175. The vapour compression refrigerator employs the following cycle
(A) Rankine (B) Carnot
(C) Reversed Rankine (D) Reversed Carnot
176. Vertical lines on pressure-enthalpy chart show constant
(A) Pressure lines (B) Temperature lines
(C) Total heat lines (D) Entropy lines
177. The undesirable property of a refrigerant is
(A) Low freezing point (B) Low viscosity
(C) High miscibility with lubricating oil (D) Low latent heat of evaporation
178. When the air is passed through an insulated chamber having sprays of water maintained at
a temperature higher than the dew point temperature of entering air but lower than its dry
bulb temperature, then the air is said to be
(A) Cooled and humidified (B) Cooled and dehumidified
(C) Heated and humidified (D) Heated and dehumidified
179. A condenser of refrigeration system rejects heat at the rate of 120 kW, while its compressor
consumes a power of 30 kW. The coefficient of performance of the system will be
(A) 1/4 (B) 1/3
(C) 3 (D) 4
180. In a saturated air-water vapour mixture, the
(A) Dry bulb temperature is higher than wet bulb temperature
(B) Dew point temperature is lower than wet bulb temperature
(C) Dry bulb, wet bulb and dew point temperature are same
(D) Dry bulb temperature is higher than dew point temperature
181. The atmospheric air at DBT is 20°C. It enters a heating coil which is maintained at 50°C. If
the air leaves the heating coil at 35°C, then what will be the efficiency of the coil?
(A) 0.6 (B) 0.22
(C) 0.35 (D) 0.5
182. A room contains 35 kg of dry air and 0.5 kg of water vapour. The total pressure and
temperature of air in the room are 100 Kpa and 25°C respectively. Given that the saturation
pressure for water at 25°C is 3.17 kPa, the relative humidity of the air in the room is:
(A) 67% (B) 55%
(C) 83% (D) 71%
183. Which of the following refrigerants have highest critical temperature?
(A) CO2 (B) SO2
(C) H2O (D) NH3
184. The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb
temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the
cooling coil, and td₃ = Dry bulb temperature of the cooling coil)
(A) (td₁ -td₃)/( td₂ -td₃) (B) (td₂ -td₃)/( td₁ -td₃)
(C) (td₃ -td₁)/( td₂ -td₃) (D) (td₃ -td₂)/( td₁ -td₃)
BEX – MASTER ] 8 [ Contd…
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185. If the value of Poisson's ratio is zero, then it means that
(A) the material is rigid
(B) the material is perfectly plastic
(C) there is no longitudinal strain in the material
(D) the longitudinal strain in the material is infinite
186. When a bar of length I and diameter d is rigidly fixed at the upper end and hanging freely,
then the total elongation produced in the bar due to its own weight is where w = weight per
unit volume of the bar.
wl wl2
(A) 2E (B) 2E
wl3 wl4
(C) 2E (D) 2E
187. A steel rod of length L and diameter D, fixed at both ends is uniformly heated to a
temperature rise of T. The Young's modulus is E and the coefficient of linear expansion is α.
The thermal stress in the rod is ____
(A) α T (B) α T E
(C) α T E L (D) 0
188. Which of the following is the correct relationship between the Young's modulus(E) and Bulk
modulus(K) of a material?
(Here: μ = Poisson's ratio) (Symbols and notations carry their usual meaning)
(A) E = 3K(1 - 2μ) (B) K = 4E(1 - 2μ)
(C) K = 3E(1 - 2μ) (D) E = 2K(1 - 2μ)
189. A steel bar of 5 mm is heated from 12°C to 50°C and it is free to expand. The bar will induce
(A) no stress (B) shear stress
(C) tensile stress (D) compressive stress
190. Two tapering bars of the same material are subjected to a tensile load P. The lengths of both
the bars are the same. The larger diameter of each of the bars is D. The diameter of bar A at
D D
its smaller end is and that of the bar B is . What is the ratio of elongation of the bar A
2 3
to that of the bar B?
(A) 3 : 2 (B) 2 : 3
(C) 4 : 9 (D) 1 : 3
191. The value of stress up to which a specified permanent set in percentage of strain remains on
unloading when the specimen is unloaded is known as:
(A) Ultimate stress (B) Proof stress
(C) Concentration stress (D) Breaking stress
192. The beam having a hinge support at one end and a roller support at other end and that hinge
support can have two reaction components, vertical and horizontal is known as:
(A) Double overhanging beams (B) Cantilever beams
(C) Overhanging beams (D) Simply supported beams
193. The bending moment of a cantilever beam of length l and carrying a gradually varying load
from zero at free end and w per unit length towards the fixed end is _______ at the fixed end.
wl wl2
(A) 2 (B) 2
wl2 wl3
(C) (D)
6 2
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194. In Double Integration method, First integration gives the value of ____
(A) deflection (B) slope
(C) twisting angle (D) diameter
195. A cantilever beam of length l is subjected to a moment M at the free end. The moment of
inertia of the beam cross-section about the neutral axis is I and the Young modulus is E. The
magnitude of the maximum deflection is.
Ml2 Ml2
(A) (B)
2EI EI
2Ml2 4Ml2
(C) EI (D) 2EI
196. Maxwell's reciprocal theorem is based on -
i. Principle of conservation of energy
ii. Principle of conservation of mass
iii. Principle of superposition
(A) (i), (ii) & (iii) (B) (i) & (iii)
(C) (i) only (D) (i) & (ii)
197. The power transmitted by a 80 mm diameter shaft at 150 rpm at a maximum shear stress of
60 N/mm2 is :
(A) 35.65 kW (B) 54.65 kW
(C) 74.65 kW (D) 94.65 Kw
198. Maximum shear stress developed on the surface of a solid circular shaft under pure torsion
is 240 MPa. If the shaft diameter is doubled, what is the maximum shear stress developed for
the same torque
(A) 30 MPa (B) 60 MPa
(C) 20 MPa (D) 15 MPa
199. Which theory is applicable for analysis of thick cylinder?
(A) Poisson’s theory (B) Lame’s theory
(C) Maxwell's theory (D) None of these
200. A thick cylinder with 10 mm internal diameter and 20 mm external diameter, is subjected to
an internal fluid pressure of 60 MPa. The hoop stress at the inner surface is
(A) 140 MPa (B) – 60 MPa
(C) 100 MPa (D) 40 MPa
201. If a thick cylindrical shell is subjected to internal pressure, then hoop stress, radial stress and
longitudinal stress at point in the thickness will be:
(A) Tensile, compressive, and compressive respectively
(B) All compressive
(C) All Tensile
(D) Tensile, compressive and tensile respectively
202. The buckling load for a given material depends upon:
(A) Slenderness ratio and modulus of elasticity
(B) Poisson's ratio and modulus of elasticity
(C) Poisson's ratio and slenderness ratio
(D) Slenderness ratio and cross sectional area
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203. A circular rod of length ‘L’ and area of cross-section ‘A’ has a modulus of elasticity ‘E’ and
coefficient of thermal expansion ‘α’. One end of the rod is fixed and other end is free. If the
temperature of the rod is increased by ΔT, then
(A) Stress developed in the rod is EαΔT and strain developed is αΔT
(B) Both stress and strain developed are zero
(C) Stress developed in the rod is zero and strain developed is αΔT
(D) Stress developed in the rod is EαΔT and strain developed is zero
204. According to the principle of transmissibility of forces, the effect of force on a body is
(A) same at every point in its line of action
(B) different at different points in its line of action
(C) minimum when it acts at the centre of gravity of the body
(D) maximum when it acts at the centre of gravity of the body
205. A framed structure is said to be perfect if the following correlation exits between the number
of joints j and the number of members m
(A) m = 2 j – 3 (B) m = 3 j - 3
(C) m = 2 j – 1 (D) m = j – 2
206. Which of the following is the correct Lami's equation?
P Q R P Q R
(A) sin θ = sin α = sinβ (B) cos θ = cos α = cos β
P Q R P Q R
(C) sin α = sin β = sinθ (D) cos α = cos β = cosθ
207. A block R of mass 100 kg is placed on a block S of mass 150 kg as shown in the figure. Block
R is tied to the wall by a massless and inextensible string PQ. If the coefficient of static friction
for all surfaces is 0.4, the minimum force F (in kN) needed to move the block S is
(A) 0.69 (B) 0.88
(C) 0.98 (D) 1.37
208. Two steel trusses, XY and YZ of identical size support a load of 200 N as shown in fig. The
length of the truss is 1 m. The force in the truss XY in Newton is
(A) 100 N (B) 200 N
(C) 150 N (D) 50 N
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209. To take the longest possible jump, an athlete should make an angle of __
(A) 90 degree with the ground (B) 60 degree with the ground
(C) 45 degree with the ground (D) 30 degree with the ground
210. The kinetic energy of a body is stated to increase by 300 percent. The corresponding increase
in the momentum of the body will be ____%
(A) 50 (B) 100
(C) 200 (D) 300
211. A thin rod of length L and mass M will have what moment of inertia about an axis passing
through one of its edges and perpendicular to rod?
(A) ML2/12 (B) ML2/16
(C) ML2/3 (D) ML2/9
212. During elastic and inelastic collision, _______ is conserved.
(A) kinetic energy (B) velocity
(C) viscosity (D) momentum
213. Two inelastic spheres of masses 10 kg each move with velocities of 15 m/s and 5 m/s
respectively in the same direction. The loss in kinetic energy when they collide is
(A) 500 Nm (B) 0 Nm
(C) 250 Nm (D) 1000 Nm
214. Two mating spur gears have 70 and 30 teeth. Their common module is 5 mm. The centre to
centre distance between the gear axis is _______
(A) 150 mm (B) 250 mm
(C) 300 mm (D) 500 mm
215. A pair of involute spur gears with 16° pressure angle and pitch in module 6 mm is in mesh.
The number of teeth on pinion is 16 and its rotational speed is 240 rpm. When the gear ratio
is 1.75, the addenda on pinion and gear wheel when the interference is just avoided will be
_______
(A) 5.46 mm (B) 4.9 mm
(C) 4.56 mm (D) None of the above
216. Which of the following is NOT a basis for classification of cams?
(A) Manner constraint of the follower (B) Follower movement in cam
(C) Weight of cam (D) Shape of cam
217. Klein’s construction is mainly used to:
(A) determine the linear velocity of piston
(B) determine the linear acceleration of piston
(C) determine the linear displacement of piston
(D) none of the above
218. An unbalanced couple of magnitude 300 N-m is noticed on a shaft of length 200 cm. The
dynamic reactions at the bearings are
(A) 300 N and -300 N (B) 300 N and 300 N
(C) 150 N and 150 N (D) 150 N and -150 N
219. Find the efficiency of a pulley system which has a mechanical advantage of 2.5 and where the
load lifts by 2.5 meters on pulling the rope by 10 m.
(A) 62.50% (B) 25.00%
(C) 40.00% (D) 100.00%
220. For a Watt governor, 15 cm height corresponds to angular speed of
(A) 9.2 rad/sec (B) 8.1 rad/sec
(C) 6.5 rad/sec (D) 7.0 rad/sec
BEX – MASTER ] 12 [ Contd…
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221. Which of the following governors is/are not suitable for high speeds?
(A) Watt governor (B) Hartnell governor
(C) Hartung governor (D) Wilson-Hartnell governor
222. The manometric efficiency of a centrifugal pump is defined as the ratio of:
(A) Manometric head to the head imparted by the impellor to the water
(B) Head imparted by the impellor to the water to the manometric head
(C) Suction head to the head imparted by the impellor to the water
(D) Head imparted by the impellor to water to the suction head
223. For discharge Q, the specific speed of the pump is N. For double the discharge with same
head, the specific speed will be:
N
(A) (B) 2N
2
N
(C) (D) 2N
2
224. Property of material due to which they can be drawn into wires, is called
(A) Elasticity (B) Plasticity
(C) Stiffness (D) Ductility
225. The ability of the material to resist penetration by another material, is called
(A) Stiffness (B) Ductility
(C) Hardness (D) Plasticity
226. Stress concentration occurs when a body is subjected to
(A) Extensive stress (B) Non-uniform stress
(C) Reverse stress (D) Fluctuating stress
227. A metal which is ductile in tension can become brittle
(A) in the presence of notches
(B) under hydrostatic compression
(C) in the presence of embrittlement agents such as hydrogen
(D) all of these
228. Silicon steel is widely used in
(A) Cutting tools (B) Connecting rods
(C) Electric industry (D) Chemical industry
229. If the surface crack causing fracture in a brittle material is made twice as deep, the fracture
strength will
(A) decrease by a factor of 2 (B) decrease by a factor of 2
(C) decrease by a factor of (D) No change
230. Fracture toughness KIC, decreases with
(A) increasing temperature (B) increasing strain rate
(C) increase in yield strength (D) increase in grain size
231. Which test is to be conducted in the laboratory for the determination of shear strength
parameters 'C' and 'ϕ' of soil?
(A) Tri-axial compression test (B) Atterbarg limit test
(C) Proctor compaction test (D) Relative density test
232. Which of the following stresses does not have any influence on strength of a material?
(A) Major principal stress (B) Minor principal stress
(C) Intermediate principal stress (D) Shearing stress
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233. The Non-Destructive Inspection technique employed during inspection of castings of tubes
and pipes to check the overall strength of a casting in resistance to bursting under hydraulic
pressure is
(A) Radiographic inspection (B) Magnetic particle inspection
(C) Fluorescent penetrant (D) Pressure testing
234. Which of the following is associated with basic metal forming process
(A) Double edged cutting (B) Welding
(C) Sintering (D) Compacting
235. Which of the following is not associated with the motion of job in cutting operation?
(A) Rotary (B) Vibratory
(C) Translator (D) Fixed
236. The cutting edges of a twist drill are known as
(A) Flanks (B) Wedges
(C) Flutes (D) Lips
237. Experimental determination of chip tool interface temperature is not possible by
(A) Method of compound tool (B) Method of moving thermocouple
(C) Photographic method (D) Radio-active method
238. Which of the following processes are included in finishing?
(A) Honig and welding (B) Polishing and lapping
(C) Coating and milling (D) Moulding and plating
239. The process of increasing the cross-sectional area of the stock at the expense of its length by
the application of force in the direction of its length is called _______.
(A) fullering (B) upsetting
(C) drawing down (D) swaging
240. Collapsible tooth paste tubes are manufactured by
(A) Direct extrusion (B) Piercing
(C) Impact extrusion (D) Indirect extrusion
241. A metal disc of 20 mm diameter is to be punched from a sheet of 2 mm thickness. The punch
and die clearance is 3%. The required punch diameter is
(A) 19.88 mm (B) 19.94 mm
(C) 20.06 mm (D) 20.12 mm
242. Spinning is carried out on
(A) Hydraulic press (B) Mechanical press
(C) Lathe (D) Milling machine
243. Match the pairs:
Processes Characteristics/Applications
P. Friction welding 1. non-consumable electrode
Q. Gas metal arc welding 2. Joining of thick plates
R. Tungsten inert gas welding 3. Consumable electrode wire
S. Electroslag welding 4. Joining of cylindrical dissimilar materials
(A) P - 4, Q - 3, R - 1, S - 2 (B) P - 4, Q - 2, R - 3, S - 1
(C) P - 2, Q - 3, R - 4, S - 1 (D) P - 2, Q - 4, R - 1, S - 3
244. In electro discharge machining, the tool is made of
(A) Plain carbon steel (B) Copper
(C) Cast iron (D) High speed steel
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245. In abrasive jet machining, as the distance between the nozzle tip and work surface increases,
the material removal rate _______
(A) Increases continuously
(B) Decreases continuously
(C) Decreases, becomes stable and then increases
(D) Increases, becomes stable and then decreases
246. Normalisation of steel is done
(A) To refine the grain structure
(B) Remove strain caused by cold working
(C) Remove dislocations caused by hot working
(D) All of the above
247. _______ is the surface hardening process that gives maximum hardness to the surface.
(A) Pack hardening (B) Nitriding
(C) Cyaniding (D) Induction hardening
248. What is the major problem in hot extrusion?
(A) Design of punch (B) Design of die
(C) Wear and tear of die (D) Wear of punch
249. Two slip gauges of 10 mm width measuring 1.000 mm and 1.002 mm are kept side by side in
contact with each other lengthwise. An optical flat is kept resting on the slip gauges as shown
in the figure. Mono-chromatic light of wavelength 0.0058928 mm used in the inspection. The
total number of straight fringes that can be observed on both slip gauges is
(A) 2 (B) 6
(C) 8 (D) 13
250. The dimensional limits on a shaft of 25h7 are
(A) 25.000, 25.021 mm (B) 25.000, 24.979 mm
(C) 25.000, 25.007 mm (D) 25.000, 24.993 mm
251. Essential condition for an interference fit is that the lower limit of the shaft should be
(A) Lesser than upper limit of the hole (B) Greater than the lower limit of the hole
(C) Lesser than the lower limit of the hole (D) Greater than the upper limit of the hole
252. What is the purpose of using autocollimator?
(A) To measure small angular differences. (B) To measure flatness.
(C) To measure concavity. (D) To check surface linearity.
253. Expressing a dimension as 25.3±0.05 mm is the case of
(A) Unilateral tolerance (B) Bilateral tolerance
(C) Limiting dimensions (D) All of the above
254. Which of the following is the most precise device for measuring length:
(A) a vernier caliper with 20 divisions on the sliding scale
(B) a screw gauge of pitch 1 mm and 100 divisions on the circular scale
(C) an optical instrument that can measure length to within a wavelength of light.
(D) All of the above
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255. Which of the following represents a form tolerance?
(A) Flatness (B) Parallelism
(C) Concentricity (D) Total run out
256. Wear allowance is provided on
(A) Go gauge (B) No go gauge
(C) Both go and no go gauge (D) When both are combined in one gauge
257. The maximum interference in mm after assembly between a bush of size 30+0.06 +0.03 mm and
+0.04
shaft of size 30−0.02 mm is
(A) 0.07 (B) 0.05
(C) 0.02 (D) 0.01
258. What does N, P and L mean in N.P.L. gauge interferometer?
(A) Nikon Pulse Laser (B) Nuclear Plasma Laboratory
(C) National Physics Laboratory (D) Nuclear Physics Laboratory
259. If load on the ball bearing is reduced to half, its life will increase to
(A) 8 times (B) 16 times
(C) 32 times (D) 64 times
260. In spur gears, the circle on which the involute is generated is called:
(A) base circle (B) clearance angle
(C) pitch circle (D) addendum circle
261. In replacing a V-belts, a complete set of new belts is used instead of replacing a single
damaged belt because.
(A) Belts are available in sets
(B) Only one belt is fitted with other used belts
(C) The new belt will carry more than its share and result in short life
(D) New and old belts will cause vibrations
262. The product of circular pitch and diametral pitch is equal to
(A) 1 (B) 1.57
(C) π (D) Infinite
263. Stress concentration factor for a machine component is dependent
(A) only on the geometry of the component
(B) only on the material of the component
(C) on geometry as well as material of the component
(D) on factors other than geometry and material of the component
264. In flange coupling, the flanges are coupled together by means of
(A) Bolts and nuts (B) Studs
(C) Headless taper bolts (D) None of these
265. In a multiple V belt drive, when a single belt is damaged, it is preferable to change the
complete set to _____.
(A) Reduce vibration (B) Reduce slip
(C) Ensure uniform loading (D) Ensure proper alignment
266. The function of a washer is to
(A) Provide cushioning effect
(B) Provide bearing area
(C) Absorb shocks and vibrations
(D) Provide sooth surface in place of rough surface
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267. Transverse fillet welded joints are designed for
(A) Tensile strength (B) Compressive strength
(C) Shear strength (D) Bending strength
268. Aircraft body is usually fabricated by
(A) Welding (B) Pre-casting
(C) Riveting (D) Casting
269. The sleeve of Muff coupling is designed as a
(A) Thin cylinder (B) Thick cylinder
(C) Solid shaft (D) Hollow shaft
270. Surface endurance limit of gear material is dependent upon its
(A) Elastic strength (B) Yield strength
(C) Brinell hardness number (D) Toughness
271. According to Indian standard specifications, 100 H6/g5 means that the
(A) Tolerance grade for the hole is 6 and for the shaft is 5
(B) Tolerance grade for the shaft is 6 and for the hole is 5
(C) Tolerance grade for the shaft is 4 to 8 and for the hole is 3 to 7
(D) Tolerance grade for the hole is 4 to 8 and for the shaft is 3 to 7
272. If the load on a ball bearing is reduced to one third, then its life would increase by
(A) 3 times (B) 27 times
(C) 9 times (D) 81 times
273. The contact ratio for gears is
(A) Zero (B) Less than one
(C) Greater than or equal to one (D) None of these
274. When bevel gears having equal teeth connect two shafts whose axes are mutually
perpendicular, then the bevel gears are known as
(A) Skew bevel gears (B) Spiral gears
(C) Miter gears (D) Zero bevel gears
275. In a 2D CAD package, clockwise circular arc of radius 5 units, specified from points A (15,
10) to B (10, 15) has its centre at:
(A) (10, 10) (B) (15,10)
(C) (15, 15) (D) (10, 15)
276. MO6 represents the following instruction in CNC programing
(A) Program stop (B) Tool change
(C) Coolant on (D) Spindle on
277. Consider the following 8086 assembly language program:
MOV AX, BB11H
MOV CX, 1122H
ADD AX, CX
HLT
The result of this program is:
(A) CX = CC33H (B) AX = CC33H
(C) CX = BB11H (D) AX = BB11H
278. NC contouring is an example of
(A) Continuous path positioning (B) Point-to-point positioning
(C) Absolute positioning (D) Incremental positioning
BEX – MASTER ] 17 [ Contd…
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279. In an intrinsic semiconductor, the Fermi level
(A) Lies at the center of forbidden energy gap
(B) Is near the conduction band
(C) Is near the valence band
(D) May be anywhere in the forbidden energy gap
280. The forbidden energy gap for germanium is
(A) 0.12 eV (B) 0.72 eV
(C) 1.11 eV (D) 1.52 eV
281. The pair of donor impurities for semiconductor material is:
(A) Gallium and Helium (B) Gallium and Indium
(C) Arsenic and Antimony (D) Arsenic and Argon
282. The ripple voltage of a full-wave rectifier with a 100 μF filter capacitor connected to a load
drawing 50 mA is:
(A) 2.4 kV (B) 4.8 kV
(C) 1.2 kV (D) 6.6 kV
283. If the input AC voltage is 10 Vrms, find the maximum voltage across the diode of a half wave
rectifier with capacitor input filter
(A) 14.1 V (B) 20 V
(C) 10 V (D) 7.07 V
284. A device whose characteristics are very close to that of an ideal voltage source is a
(A) SCR (B) FET
(C) MOSFET (D) Zener diode
285. What is the current through the Zener diode?
(A) 0 mA (B) 7 mA
(C) 8.3 mA (D) 13 mA
286. To amplify voltage, current and power signals using BJT amplifiers, which of the following
configurations are used?
(A) common collector, common base and common emitter
(B) common base, common emitter and common collector
(C) common emitter, common collector and common base
(D) common base, common collector and common emitter
287. The number of depletion layers in a transistor is _______.
(A) Two (B) Three
(C) Four (D) Five
288. Under low level injection assumption, the injected minority carrier current for an extrinsic
semiconductor is essentially the
(A) Diffusion current (B) Drift current
(C) Recombination current (D) Induced current
BEX – MASTER ] 18 [ Contd…
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289. The time by which the activity completion time can be delayed without affecting the start of
succeeding activities is known as
(A) Duration (B) Total float
(C) Free float (D) Interfering float
290. The Operations research technique which helps in minimizing total waiting and service costs
is
(A) Queuing Theory (B) Decision Theory
(C) Game Theory (D) Network Theory
291. Pessimistic time and optimistic time of completion of an activity are given as 10 days and 4
days respectively, the variance of the activity will be
(A) 1 (B) 6
(C) 12 (D) 18
292. In PERT the activity distribution is
(A) Binomial (B) Normal
(C) Poisson (D) Beta
293. In a transportation problem with 4 supply points and 5 demand points, how many number
of constraints are required in its formulation?
(A) 20 (B) 1
(C) 0 (D) 9
294. Vogel’s approximation method is connected with
(A) Assignment problem (B) Inventory problem
(C) Transportation problem (D) PERT
295. Activities A, B, and C are the immediate predecessors for Y activity. If the earliest finishing
time for the three activities are 12, 15, and 10, then what will be the earliest starting time for
Y?
(A) 10 (B) 15
(C) 12 (D) 18.5
296. A dummy activity is used in PERT network to describe
(A) Precedence relationship (B) Necessary time delay
(C) Resource restriction (D) Resource idleness
297. Usually, stronger constituent of a composite is:
(A) Matrix (B) Reinforcement
(C) Both are of equal strength (D) Fillers
298. Electron beam machining is a process which can be categories as:
(A) Thermal energy based process (B) Mechanical energy based process
(C) Chemical energy based process (D) Electro-chemical process
299. In Lead Acid Batteries, the Electrolyte used is
(A) Sulphuric Acid (B) Hydrochloric acid
(C) Nitric acid (D) Acetic acid
300. What does PHEV stands for?
(A) Plug-in Hybrid Electronic Vehicles (B) Plug-in Hybrid Electric Vehicles
(C) Plug-out Hybrid Electronic Vehicles (D) Plug-out Hybrid Electric Vehicles
BEX – MASTER ] 19 [ Contd…
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Gujarat Public Service Commission
Assistant Engineer (Mechanical), Class-2 (GWSSB) (Advt No. 26/2023-24) Exam Date:18-08-2023
BEX(CBRT)
Final Answer Key for Question No. 01- 300 is declared as below Series:M
Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer Q.No. Answer
1 B 31 C 61 C 91 C 121 A 151 D 181 D 211 C 241 A 271 A
2 C 32 A 62 A 92 D 122 C 152 B 182 D 212 D 242 C 272 B
3 A 33 B 63 C 93 C 123 A 153 C 183 C 213 C 243 A 273 C
4 D 34 C 64 D 94 A 124 C 154 B 184 B 214 B 244 B 274 C
5 C 35 B 65 A 95 B 125 D 155 B 185 A 215 C 245 D 275 C
6 D 36 D 66 B 96 D 126 B 156 A 186 B 216 C 246 D 276 B
7 * 37 C 67 C 97 C 127 C 157 D 187 B 217 B 247 B 277 B
8 A 38 A 68 A 98 D 128 B 158 B 188 A 218 D 248 B 278 A
9 C 39 B 69 D 99 B 129 B 159 D 189 A 219 A 249 A 279 A
10 D 40 A 70 C 100 C 130 C 160 D 190 B 220 B 250 B 280 B
11 B 41 D 71 A 101 B 131 B 161 D 191 B 221 C 251 D 281 C
12 A 42 C 72 C 102 A 132 B 162 B 192 D 222 A 252 A 282 C
13 B 43 B 73 B 103 C 133 A 163 D 193 C 223 B 253 B 283 A
14 C 44 C 74 C 104 A 134 C 164 D 194 B 224 D 254 C 284 D
15 D 45 A 75 A 105 B 135 B 165 C 195 A 225 C 255 A 285 B
16 B 46 D 76 D 106 A 136 A 166 B 196 B 226 B 256 A 286 D
17 A 47 B 77 C 107 B 137 C 167 B 197 D 227 A 257 D 287 A
18 B 48 A 78 B 108 D 138 C 168 C 198 A 228 C 258 C 288 A
19 D 49 D 79 A 109 A 139 D 169 B 199 B 229 A 259 A 289 C
20 A 50 C 80 D 110 C 140 A 170 C 200 C 230 B 260 A 290 A
21 C 51 B 81 C 111 B 141 D 171 C 201 D 231 A 261 C 291 A
22 A 52 D 82 A 112 D 142 B 172 A 202 A 232 C 262 C 292 D
23 D 53 A 83 B 113 A 143 C 173 A 203 C 233 D 263 C 293 D
24 A 54 C 84 C 114 A 144 C 174 D 204 A 234 A 264 A 294 C
25 B 55 D 85 B 115 A 145 B 175 C 205 A 235 B 265 C 295 B
26 C 56 B 86 A 116 A 146 B 176 C 206 C 236 D 266 B 296 A
27 D 57 A 87 C 117 B 147 A 177 D 207 D 237 D 267 A 297 B
28 B 58 B 88 D 118 C 148 C 178 A 208 B 238 B 268 C 298 A
29 A 59 D 89 A 119 D 149 B 179 D 209 C 239 B 269 D 299 A
30 D 60 B 90 B 120 C 150 B 180 C 210 B 240 C 270 C 300 B
* Cancelled Question(s) Revised Answer(s) is(are) Highlighted
Gandhinagar Date:04-11-2023Page 1 of 31
Source: Gujarat Public Service Commission. Question paper published by Gujarat Public Service Commission.