MCQOPTIONS
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MCQOPTIONS
This section includes 198 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Discharge of a centrifugal pump is (where N = Speed of the pump impeller) |
| A. | directly proportional to N |
| B. | inversely proportional to N |
| C. | directly proportional to N² |
| D. | inversely proportional to N² |
| Answer» B. inversely proportional to N | |
| 102. |
In a reaction turbine, the draft tube is used |
| A. | to run the turbine full |
| B. | to prevent air to enter the turbine |
| C. | to increase the head of water by an amount equal to the height of the runner outlet above the tail race |
| D. | to transport water to downstream |
| Answer» D. to transport water to downstream | |
| 103. |
The power produced by the reaction turbine is __________ to the head of water. |
| A. | directly proportional |
| B. | inversely proportional |
| C. | Can't say |
| D. | None of these |
| Answer» B. inversely proportional | |
| 104. |
In an inward flow reaction turbine |
| A. | the water flows parallel to the axis of the wheel |
| B. | the water enters at the centre of the wheel and then flows towards the outer periphery of the wheel |
| C. | the water enters the wheel at the outer periphery and then flows towards the centre of the wheel |
| D. | the flow of water is partly radial and partly axial |
| Answer» D. the flow of water is partly radial and partly axial | |
| 105. |
In a reciprocating pump, air vessels are used to |
| A. | smoothen the flow |
| B. | reduce suction head |
| C. | increase delivery head |
| D. | reduce acceleration head |
| Answer» E. | |
| 106. |
Which type of the pump is different from others in the same group? |
| A. | Screw pump |
| B. | Gear pump |
| C. | Cam and piston pump |
| D. | Plunger pump |
| Answer» E. | |
| 107. |
In a centrifugal pump, the regulating valve is provided on the |
| A. | casing |
| B. | delivery pipe |
| C. | suction pipe |
| D. | impeller |
| Answer» C. suction pipe | |
| 108. |
A Pelton wheel with one nozzle is preferred for a specific speed between 35 to 60 r.p.m. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 109. |
If the Francis turbine is run below 50 percent head for a long period, it will not only lose its efficiency but also the cavitation danger will become more serious. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 110. |
A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit discharge of wheel is |
| A. | 0.25 m³/s |
| B. | 0.5 m³/s |
| C. | 1.5 m³/s |
| D. | 2.5 m³/s |
| Answer» B. 0.5 m³/s | |
| 111. |
The type of centrifugal pump preferred for a specific speed of 20 r.p.m. is |
| A. | slow speed pump with radial flow at outlet |
| B. | medium speed pump with radial flow at outlet |
| C. | high speed pump with radial flow at outlet |
| D. | high speed pump with axial flow at outlet |
| Answer» B. medium speed pump with radial flow at outlet | |
| 112. |
The water in a jet propelled boat is drawn through the openings facing the direction of motion of the boat. The efficiency of propulsion is given by |
| A. | 2V/(vr - v) |
| B. | 2V/(vr + v) |
| C. | V/(vr - v) |
| D. | V/(vr + v) |
| Answer» C. V/(vr - v) | |
| 113. |
If the net positive suction head (NPSH) requirement for the pump is not satisfied, then |
| A. | no flow will take place |
| B. | cavitation will be formed |
| C. | efficiency will be low |
| D. | excessive power will be consumed |
| Answer» C. efficiency will be low | |
| 114. |
In order to avoid cavitation in centrifugal pumps |
| A. | the suction pressure should be high |
| B. | the delivery pressure should be high |
| C. | the suction pressure should be low |
| D. | the delivery pressure should be low |
| Answer» B. the delivery pressure should be high | |
| 115. |
Which of the following turbine is preferred for a specific speed of 60 to 300 r.p.m.? |
| A. | Pelton wheel |
| B. | Francis turbine |
| C. | Kaplan turbine |
| D. | none of these |
| Answer» C. Kaplan turbine | |
| 116. |
The number of buckets on the periphery of a Pelton wheel is given by |
| A. | (D/2d) + 5 |
| B. | (D/2d) + 10 |
| C. | (D/2d) + 15 |
| D. | (D/2d) + 20 |
| Answer» D. (D/2d) + 20 | |
| 117. |
The action of a centrifugal pump is that of a reversed reaction turbine. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 118. |
The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is |
| A. | slow speed with radial flow at outlet |
| B. | medium speed with radial flow at outlet |
| C. | high speed with radial flow at outlet |
| D. | high speed with mixed flow at outlet |
| Answer» E. | |
| 119. |
The speed ratio in case of Francis turbine varies from |
| A. | 0.15 to 0.3 |
| B. | 0.4 to 0.5 |
| C. | 0.6 to 0.9 |
| D. | 1 to 1.5 |
| Answer» D. 1 to 1.5 | |
| 120. |
A Kaplan turbine is preferred for a specific speed of 300 to 1000 r.p.m. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 121. |
A jet of water enters and leaves a fixed curved vane tangentially. The force of the jet along normal to the vane is (where α and β = Inlet and outlet angles of the jet respectively) |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 122. |
In an impulse turbine, the jet of water impinges on the bucket with a low velocity and after flowing over the vanes, leaves with a high velocity. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 123. |
A Francis turbine is used when the available head of water is |
| A. | 0 to 25 m |
| B. | 25 m to 250 m |
| C. | above 250 m |
| D. | none of these |
| Answer» C. above 250 m | |
| 124. |
The specific speed from 160 to 500 r.p.m. of a centrifugal pump indicates that the pump is |
| A. | slow speed with radial flow at outlet |
| B. | medium speed with radial flow at outlet |
| C. | high speed with radial flow at outlet |
| D. | high speed with axial flow at outlet |
| Answer» E. | |
| 125. |
The principle of jet propulsion is used in driving the ships and aeroplanes. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 126. |
A hydraulic coupling belongs to the category of |
| A. | power absorbing machines |
| B. | power developing machines |
| C. | energy transfer machines |
| D. | energy generating machines |
| Answer» D. energy generating machines | |
| 127. |
In the casing of a centrifugal pump, the kinetic energy of the water is converted into pressure energy before the water leaves the casing. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 128. |
Discharge of a centrifugal pump is |
| A. | directly proportional to diameter of its impeller |
| B. | inversely proportional to diameter of its impeller |
| C. | directly proportional to (diameter)² of its impeller |
| D. | inversely proportional to (diameter)² of its impeller |
| Answer» E. | |
| 129. |
A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit power of the wheel is |
| A. | 0.25 kW |
| B. | 0.75 kW |
| C. | 1.75 kW |
| D. | 3.75 kW |
| Answer» D. 3.75 kW | |
| 130. |
The static head of a centrifugal pump is equal to the __________ of suction head and delivery head. |
| A. | product |
| B. | difference |
| C. | sum |
| D. | None of these |
| Answer» D. None of these | |
| 131. |
The ratio of actual work available at the turbine to the energy imparted to the wheel is known as __________ efficiency. |
| A. | hydraulic |
| B. | mechanical |
| C. | overall |
| D. | None of these |
| Answer» C. overall | |
| 132. |
Geometric similarity is said to exist between the model and the prototype, if both of them |
| A. | have identical velocities |
| B. | are equal in size and shape |
| C. | are identical in shape, but differ only in size |
| D. | have identical forces |
| Answer» D. have identical forces | |
| 133. |
The capacity of a hydraulic accumulator is generally specified as the maximum amount of energy stored. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 134. |
The maximum efficiency of jet propulsion of a ship with inlet orifices at right angles to the direction of motion of ship, is |
| A. | 40% |
| B. | 50% |
| C. | 60% |
| D. | 80% |
| Answer» C. 60% | |
| 135. |
The breast water wheels are those in which the wheel runs partly by the weight of water and partly by the impulse of water. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 136. |
The ratio of quantity of liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as |
| A. | manometric efficiency |
| B. | mechanical efficiency |
| C. | overall efficiency |
| D. | volumetric efficiency |
| Answer» E. | |
| 137. |
Slip of a reciprocating pump is defined as the |
| A. | ratio of actual discharge to the theoretical discharge |
| B. | sum of actual discharge and the theoretical discharge |
| C. | difference of theoretical discharge and the actual discharge |
| D. | product of theoretical discharge and the actual discharge |
| Answer» D. product of theoretical discharge and the actual discharge | |
| 138. |
The efficiency of a centrifugal pump will be maximum when the blades are bent backward. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 139. |
Multi-stage centrifugal pumps are used to |
| A. | give high discharge |
| B. | produce high heads |
| C. | pump viscous fluids |
| D. | all of these |
| Answer» C. pump viscous fluids | |
| 140. |
The specific speed of a centrifugal pump, delivering 750 litres of water per second against a head of 15 metres at 725 r.p.m., is |
| A. | 24.8 r.p.m. |
| B. | 48.2 r.p.m |
| C. | 82.4 r.p.m. |
| D. | 248 r.p.m |
| Answer» D. 248 r.p.m | |
| 141. |
When the speed of the pump increases, its net positive suction head (NPSH) requirement decreases. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 142. |
Theoretical power required (in watts) to drive a reciprocating pump is (where w = Specific weight of liquid to be pumped in N/m³, Q = Discharge of the pump in m³/s, Hs = Suction head in metres, and Hd = Delivery head in metres) |
| A. | wQHs |
| B. | wQHd |
| C. | wQ(Hs - Hd) |
| D. | wQ(Hs + Hd) |
| Answer» E. | |
| 143. |
The maximum number of jets, generally, employed in an impulse turbine without jet interference are |
| A. | two |
| B. | four |
| C. | six |
| D. | eight |
| Answer» D. eight | |
| 144. |
In a reciprocating pump, air vessels are fitted to the suction pipe and delivery pipe close to the cylinder of the pump. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 145. |
Discharge (Q) of a centrifugal pump is given by (where D = Diameter of impeller at inlet, b = Width of impeller at inlet, and Vf = Velocity of flow at inlet) |
| A. | Q = π.D.Vf |
| B. | Q = π.b.Vf |
| C. | Q = π.D.b.Vf |
| D. | Q = D.b.Vf |
| Answer» D. Q = D.b.Vf | |
| 146. |
A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the |
| A. | kinetic head |
| B. | velocity head |
| C. | manometric head |
| D. | static head |
| Answer» D. static head | |
| 147. |
In a Kaplan turbine runner, the number of blades are generally between |
| A. | 2 to 4 |
| B. | 4 to 8 |
| C. | 8 to l6 |
| D. | 16 to 24 |
| Answer» C. 8 to l6 | |
| 148. |
If Hg is the gross or total head and hf is the head lost due to friction, then net or effective head (H) is given by |
| A. | H = Hg/hf |
| B. | H = Hg x hf |
| C. | H = Hg + hf |
| D. | H = Hg - hf |
| Answer» E. | |
| 149. |
Power required to drive a centrifugal pump is directly proportional to __________ of its impeller. |
| A. | diameter |
| B. | square of diameter |
| C. | cube of diameter |
| D. | fourth power of diameter |
| Answer» E. | |
| 150. |
The mechanical efficiency of an impulse turbine is |
| A. | ratio of the actual power produced by the turbine to the energy actually supplied by the turbine |
| B. | ratio of the actual work available at the turbine to the energy imparted to the wheel |
| C. | ratio of the Work done on the wheel to the energy of the jet |
| D. | none of the above |
| Answer» C. ratio of the Work done on the wheel to the energy of the jet | |