mechanical engineering MCQs – Page 84

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

4151. In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by_______________?
comments icon0
A. trimming the impeller size to the required size by machining

B. designing new impeller

C. none of the above

D. not possible

E. some other alterations in the impeller

4152. For starting an axial flow pump, its delivery valve should be____________________?
comments icon0

A. closed

B. partly open and partly closed

C. depends on starting condition and flow desired

D. could be either open or closed

E. open
4153. The flow rate in gear pump___________________?
comments icon0

A. none of the above

B. decreases with increase in pressure

C. unpredictable

D. increases with increase in pressure

E. more or less remains constant with in-crease in pressure
4154. Medium specific speed of a pump implies it is_________________?
comments icon0

A. axial flow pump

B. any one of the above

C. mixed flow pump

D. centrifugal pump

E. none of the above

4155. The horse power required in above case will be___________________?
comments icon0
A. 0.75 B.H.P.

B. B.H.P./0.75

C. 1.5 B.H.P.

D. same

E. none of the above

4156. Saving of work done and power by fitting an air vessel to single acting reciprocating pump is of the order of__________________?
comments icon0

A. 39.20%

B. 49.20%

C. 84.8%

D. 91.6%.

E. 68.80%

4157. Hydraulic accumulator is used for____________________?
comments icon0

A. accumulating hydraulic energy

B. supplying energy when main supply fails

C. accumulating oil

D. generally high pressures to operate hydraulic machines

E. supplying large quantities of oil for very short duration

4158. Runaway speed of a hydraulic turbine is_________________?
comments icon0

A. the speed corresponding to maximum overload permissible

B. the speed at which turbine runner will be damaged

C. none of the above.

D. full load speed

E. the speed if the turbine runner is allowed to revolve freely without load and with the wicket gates wide open
4159. Francis, Kaplan and propeller turbines fall under the category of___________________?
comments icon0

A. Reaction-cum-impulse turbines

B. Mixed flow turbines

C. Reaction turbines

D. Impulse turbines

E. Axial flow turbines

4160. In a centrifugal pump, the liquid enters the pump__________________?
comments icon0

A. at the top

B. at the bottom

C. at the center

D. none of the above

E. from sides

4161. According to fan laws, for fans having constant wheel diameter, the pressure varies________________?
comments icon0

A. square root of fan speed

B. directly as fan speed

C. square of fan speed

D. none of the above

E. cube of fan speed

4162. The specific speed of turbine is defined as the speed of a unit___________________?
comments icon0

A. of such a size that it delivers unit dis-charge at unit power

B. of such a size that it produces unit horse power with unit head

C. none of the above

D. of such a size that it requires unit power per unit head

E. of such a size that it delivers unit dis-charge at unit head

4163. Lancing is the operation of _________________?
comments icon0
A. cutting a sheet of metal through part of its length and then bending the cut portion

B. cutting a sheet of metal in a straight line along the length

C. removal of metal to the desired shape from the edge of a plate

D. bending a sheet of metal along a curved axis

4164. A file removes the metal during___________________?
comments icon0

A. both forward and return strokes

B. forward stroke

C. return stroke

D. none of these

4165. A neutral flame is obtained by supplying___________________?
comments icon0

A. more volume of acetylene and less volume of oxygen

B. none of the above

C. more volume of oxygen and less volume of acetylene

D. equal volumes of oxygen and acetylene
4166. The shrinkage allowance for cast iron pattern is________________?
comments icon0

A. 15 mm/m

B. 10 mm/m

C. 26 mm/m

D. 20 mm/m

4167. The operation of straightening a curved sheet metal, is known as____________________?
comments icon0

A. coining

B. planishing

C. squeezing

D. drawing

4168. Tandem drawing of wires and tubes is necessary because_________________?
comments icon0
A. annealing is needed between stages

B. it is not possible to reduce at one stage

C. accuracy in dimensions is not possible otherwise

D. surface finish improves after every drawing stage

4169. Which of the following statement is wrong ?
comments icon0

A. all of these

B. The mortise gauge has two scribing pins

C. An auger is a planning tool

D. The gouges are chisels with a hollow shaped blade

4170. The cold working of metals is carried out_________________?
comments icon0

A. at the recrystallisation temperature

B. below the recrystallisation temperature

C. above the recrystallisation temperature

D. at any temperature

4171. In a _____________ , both cutting and non-cutting operations are performed at one station of the press in every stroke of the ram?
comments icon0

A. progressive die

B. combination die

C. simple die

D. compound die

4172. In spot welding, the spacing between two spot weld should not be less than _______________?
comments icon0

A. 1.5d

B. d

C. 3d

D. 6d

4173. In vapour compression cycle, the conditii of refrigerant is saturated liquid________________?
comments icon0

A. before entering the expansion valve

B. after passing through the expansion throttle valve

C. before entering the compressor

D. after passing through the condenser

E. before passing through the condensei

4174. Most of the domestic refrigerators work on the following refrigeration system _________________?
comments icon0
A. vapour compression

B. electrolux refrigerator

C. dual cycle

D. carnot cycle

E. vapour absorption

4175. Allowable pressure on high-pressure side or ammonia absorption system is of the order of_________________?
comments icon0

A. 2-4 bars

B. 7-10 bars

C. 5-6 bars

D. atmospheric pressure

E. slightly above atmospheric pressure

4176. If a heat pump cycle operates between the condenser temperature of +27C and evaporator temperature of 23C, then the Carnot COP will be_________________?
comments icon0

A. 1.2

B. 6

C. 10

D. 0.2

E. 5

4177. Aqua ammonia is used as refrigerant in the following type of refrigeration system_________________?
comments icon0

A. compression

B. direct

C. absorption

D. none of the above

E. indirect

4178. In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is_____________________?
comments icon0

A. there is no such consideration

B. pone of the above

C. more than or equal to 3.65 kg

D. less than 2 kg

E. more than 10 kg

4179. A refrigerant should have _____________________?
comments icon0

A. Tow specific heat of liquid

B. low specific volume of vapour

C. k up the wrong statement ?

D. high latent heat of vaporisation

E. higher critical temperature

F. high boiling point
4180. One ton refrigeratiqn corresponds to_________________?
comments icon0
A. 50 kcal/min

B. 80 kcal/min

C. 80 kcal/hr

D. 50 kcal/kr

E. 1000 kcal/day

4181. A refrigeration cycle operates between condenser temperature of + 27C and evaporator temperature of- 23C. The Cannot coefficient of performance of cycle will be_________________?
comments icon0

A. 6

B. 5

C. 0.2

D. 10

E. 1.2

4182. Critical temperature is the temperature above which _____________________?
comments icon0

A. none of the above

B. water will evaporate

C. a gas will immediately liquefy

D. water will never evaporate

E. a gas will never liquefy
4183. The COP of a domestic refrigerator___________________?
comments icon0

A. is equal to 1

B. depends upon the make

C. is less than 1

D. is more than 1

E. depends upon the weather conditions

4184. The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is_________________?
comments icon0

A. unpredictable

B. same

C. more or less depending on ambient conditions

D. more

E. less
4185. The evolution of heat of solution takes place in ammonia absorption plant when _____________________?
comments icon0

A. lithium bromide is driven out of solution

B. lithium bromide mixes with ammonia

C. ammonia vapour goes into solution

D. ammonia vapour is driven out of solution

E. weak solution mixes with strong solution

4186. Vertical lines on pressure-enthalpy chart show constant_______________?
comments icon0

A. pressure lines

B. volume lines

C. total heat lines

D. temperature lines

E. entropy lines

4187. The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will______________________?
comments icon0
A. increase

B. unpredictable

C. remain unaffected

D. may increase or decrease depending on the type of refrigerant used

E. decrease

4188. Clapeyron equation is applicable for registration at___________________?
comments icon0
A. saturation point of vapor

B. saturation point of liquid

C. critical point

D. sublimation temperature

E. triple point

4189. Presence of moisture in a refrigerant affects the working of___________________?
comments icon0
A. expansion valve

B. heat transfer

C. evaparator

D. compressor

E. condenser

4190. For obtaining high COP, the pressure range of compressor should be_______________?
comments icon0
A. low

B. high

C. any value

D. there is no such criterion

E. optimum

4191. In vapor compression cycle, the condition of refrigerant is very wet vapor________________?
comments icon0

A. before entering the expansion valve

B. after passing through the condenser

C. before entering the compressor

D. before passing through the condenser

E. after passing through the expansion or throttle valve

4192. The bank of tubes at the back of domestic refrigerator are _________________?
comments icon0
A. condenser tubes

B. refrigerant cooling tubes

C. capillary tubes

D. evaporator tubes

E. throttling device

4193. For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then_________________?
comments icon0
A. perfectly tight vapour seal should be used

B. smaller cabinet should be used

C. refrigerant with high boiling point must be used

D. refrigerant with lower evaporation temperature should be used

E. bigger cabinet should be used

4194. Vapor compression refrigeration is some what like ____________________?
comments icon0

A. Rankine cycle

B. reversed Camot cycle

C. none of the above

D. reversed Rankine cycle

E. Carnot cycle

4195. In vapor compression cycle, the condition of refrigerant is high pressure saturated liquid________________?
comments icon0
A. before entering the expansion valve

B. after passing through the condenser

C. before passing through the condenser

D. before entering the compressor

E. after passing through the expansion or thiottle valve

4196. In S.J. unit, one ton of refrigeration is equal to___________________?
comments icon0
A. 210 kJ/min

B. 420 kJ/min

C. 840 kJ/min

D. 105 kJ/min

E. 21 kJ/min

4197. Condensing temperature in a refrigerator is the temperature_________________?
comments icon0
A. at which refrigerant gas becomes liquid

B. of evaporator

C. of freezing zone

D. of cooling medium

E. condensing temperature of ice

4198. Ammonia-absorption refrigeration cycle requires__________________?
comments icon0

A. none of the above

B. zero work input

C. maximum work input

D. very little work input

E. nearly same work input as for vapour compression cycle

4199. Which of the following cycles uses air as the refrigerant__________________?
comments icon0
A. Bell-coleman

B. Carnot

C. Ericsson

D. Stirling

E. none of the above

4200. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice_________________?
comments icon0

A. in 10 hours

B. in 1 minute

C. in 1 hour

D. in 24 hours

E. in 12 hours