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Multiple choice question for engineering

Set 1

1. Fast breeder nuclear reactors using enriched uranium as fuel may contain upto a maximum of __________ percent of U-235 (i.e. fissile material).
a) 15
b) 45
c) 65
d) 85

View Answer

Answer: d [Reason:] Fast breeder nuclear reactors using enriched uranium as fuel may contain upto a maximum of 85 percent of U-235 (i.e. fissile material).

2. __________ have the same mass number, but different nuclear charge
a) Isotones
b) Isobars
c) Isotopes
d) Isoemtropic

View Answer

Answer: b [Reason:] Isobars have the same mass number, but different nuclear charge.

3. Atoms with same number of neutrons, but different number of nucleons are called
a) Isobars
b) Isotones
c) Isotopes
d) Isoters

View Answer

Answer: b [Reason:] Atoms with same number of neutrons, but different number of nucleons are called Isotones.

4. The half-life period of a radioactive substance is best determined by counting the number of alpha particles emitted per second in a Geiger Muller counter from its known quantity. If the half-life period of a radioactive substance is one month, then
a) it will completely disintegrate in two months
b) l/8th of it will remain intact at the end of four months
c) 3/4th of it will disintegrate in two months
d) it will completely disintegrate in four months

View Answer

Answer: a [Reason:] The half-life period of a radioactive substance is best determined by counting the number of alpha particles emitted per second in a Geiger Muller counter from its known quantity. If the half-life period of a radioactive substance is one month, then it will completely disintegrate in two months.

5. Which of the following ores contains maximum percentage of uranium?
a) Rescolite
b) Thorium
c) Pitchblende
d) Carnotite

View Answer

Answer: c [Reason:] Pitchblende contains the maximum percentage of Uranium.

6. Percentage of U-238 in natural uranium is around
a) 29.71
b) 99.29
c) 0.015
d) 0.71

View Answer

Answer: c [Reason:] Natural Uranium contains around 0.015% of U-238.

7. Uranium ore is currently mined & concentrated at
a) Khetri
b) Alwaye
c) Ghatsilla
d) Jadugoda

View Answer

Answer: d [Reason:] Uranium ore is currently mined & concentrated at Jadugoda.

8. Graphite is used in nuclear reactor as
a) lubricant
b) fuel
c) retarder of neutron velocity
d) insulation lining of the reactor

View Answer

Answer: c [Reason:] Graphite is used in nuclear reactor as retarder of neutron velocity.

9. A fast breeder reactor employs
a) U-235 as a fuel
b) water as a coolant
c) graphite as a moderator
d) none of the mentioned

View Answer

Answer: a [Reason:] U-235 is used as a fuel in a fast breeder reactor.

10. A radioactive isotope undergoes decay with respect to time following __________ law
a) logarithmic
b) exponential
c) inverse square
d) linear

View Answer

Answer: b [Reason:] A radioactive isotope undergoes decay with respect to time following exponential law.

11. U-235 content in enriched uranium, that is normally used in power reactors (e.g., at Tarapur atomic power plant), is about __________ percent.
a) 50
b) 3
c) 85
d) 97

View Answer

Answer: b [Reason:] U-235 content in enriched uranium, that is normally used in power reactors (e.g., at Tarapur atomic power plant), is about 3 percent.

12. The half-life period of a radioactive element is 100 days. After 400 days, one gm of the element will be reduced to __________ gm.
a) 1/2
b) 1/4
c) 1/8
d) 1/16

View Answer

Answer: d [Reason:] The half-life period of a radioactive element is 100 days. After 400 days, one gm of the element will be reduced to1/16 gm.

13. Which of the following is a non-fissile material?
a) Pu-239
b) U-235
c) U-232
d) Th-232

View Answer

Answer: d [Reason:] Of the mentioned fuels, only Th-232 is the fissile nuclear fuel.

14. Fast breeder reactors are most usable in India, because of our largest __________ deposits.
a) Uranium
b) Plutonium
c) Thorium
d) None of the mentioned

View Answer

Answer: c [Reason:] Fast breeder reactors are most usable in India, because of our largest Thorium deposits.

15. The main ore of thorium is?
a) Magnetite
b) Monazite Sand
c) Pitchblende
d) None of the mentioned

View Answer

Answer: b [Reason:] Monazite Sand is the main ore of Thorium.

Set 2

1. Ideal ‘Rankine Cycle’ is a __________ process.
a) Reversible
b) Irreversible
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: a [Reason:] Ideal Rankine Cycle is a reversible process.

2. For analytical purposes, the Rankine Cycle is assumed to be in?
a) Unsteady flow operation
b) Turbulent flow operation
c) Steady flow operation
d) Laminar flow operation

View Answer

Answer: c [Reason:] For analytical purposes , always steady flow operation is considered, as in unsteady flow, the various fluid properties vary considerably which remain same when the steady flow operation is assumed.

3. The net work done in a Rankine Cycle is the difference of?
a) Condenser work & Boiler work
b) Boiler work & Pump work
c) Turbine Work & Pump work
d) Condenser work & Pump work

View Answer

Answer: c [Reason:] The net work done in a Rankine Cycle is given by, Wnet = Wt – Wp.

4. In a Rankine Cycle, heat input is provided to?
a) Condenser
b) Pump
c) Turbine
d) Boiler

View Answer

Answer: d [Reason:] As the heating of the liquid working fluid occurs in the Boiler, the heat input is provided to the Boiler for the same.

5. In a Rankine Cycle, heat output is obtained from?
a) Condenser
b) Boiler
c) Turbine
d) Pump

View Answer

Answer: a [Reason:] As the heated water comes to the condenser, it loses its heat & gets condensed. The heat output is obtained from Condenser.

6. The water that flows from the Pump is?
a) Compressible
b) Incompressible
c) Unsteady
d) None of the mentioned

View Answer

Answer: b [Reason:] The water flowing through the pump is incompressible so as to extract work from the turbine.

7. Steam Rate is the reciprocal of _________
a) Net work done
b) Heat extracted from condenser
c) Heat given to reciprocal
d) Work done by turbine.

View Answer

Answer: a [Reason:] Steam Rate is given by, Steam Rate = 1/Wnet.

8. Which of these is sometimes neglected?
a) Turbine work
b) Pump work
c) Condenser heat
d) Boiler heat

View Answer

Answer: b [Reason:] Pump Work is very small as compared to Turbine Work & so is often neglected.

9. Efficiency of a Rankine Cycle is also expressed as__________
a) Capacity Ratio
b) Heat Rate
c) Heat Ratio
d) Steam Rate

View Answer

Answer: b [Reason:] The relation between Heat Rate & Efficiency is, Heat Rate = Efficiency of a Rankine Cycle.

10. Steam Power Plants are more popular in electric power generation because
a) Work output of turbine is very large than work input to the pump
b) Work output of turbine is very small than work input to the pump
c) Work output of turbine is equal to work input to the pump
d) None of the mentioned.

View Answer

Answer: a [Reason:] In a Steam Power Plant, the positive difference of turbine work & pump work makes it useful in electricity generation.

11. The most common type of Evaporator is?
a) Flooded Evaporator
b) Plate Evaporator
c) Coil Evaporator
d) Brine Evaporator

View Answer

Answer: b [Reason:] The most common type is a coil winding on a plate & so the name ‘plate evaporator’.

12. In Rankine Cycle, water is converted to saturated liquid in ___________
a) Evaporator
b) Economizer
c) Superheater
d) Preheater

View Answer

Answer: b [Reason:] The saturation of water occurs in an Economizer in a Rankine Cycle.

13. If Evaporator & Condenser pressures are p & q, the intercooler pressure P is given as?
a) P=pq
b) P=p/q
c) P=(pq)(1/2)
d) P=p2q

View Answer

Answer: c [Reason:] The relation between Intercooler pressure, Evaporator & Condenser is, P = (pq)(1/2).

14. Phase change at constant pressure takes place in?
a) Economiser
b) Evaporator
c) Superheater
d) Air-Preheater

View Answer

Answer: c [Reason:] Superheater undergoes a change in phase at constant pressure.

15. Which of these factors don’t cause Internal Irreversibility of a Rankine cycle?
a) Throttling
b) Mixing
c) Fluid Friction
d) Fluid flow

View Answer

Answer: d [Reason:] The Rankine cycle is an Irreversible cycle. For a cycle to be irreversible naturally throttling, mixing & friction in fluids are the factors that cause this Irreversibility.

Set 3

1. External Thermal Irreversibility can be removed by which of the following process?
a) Reheat
b) Regeneration
c) Pre-heat
d) None of the mentioned

View Answer

Answer: b [Reason:] In the process of regeneration, energy is exchanged internally between the expanding fluid in the turbine & the compressed fluid before heat addition.

2. When is the relation between mean temperature of heat addition (T) with regeneration & without regeneration?
a) (T)with regeneration is independent of(t)without regeneration
b) (T)with regeneration > (t)without regeneration
c) (T)with regeneration < (t)without regeneration
d) (T)with regeneration = (t)without regeneration

View Answer

Answer: b [Reason:] The efficiency of the regenerative cycle will be higher than that of the Rankine cycle. Hence, the relation between mean temperature of heat addition (T) with regeneration & without regeneration is, (T)with regeneration > (t)without regeneration.

3. What is the relation between energy gain of feedwater & energy given off by vapour in condensation?
a) energy gain of feedwater > energy given off by vapour in condensation
b) energy gain of feedwater < energy given off by vapour in condensation
c) energy gain of feedwater = energy given off by vapour in condensation
d) none of the mentioned

View Answer

Answer: c [Reason:] Here heaters are assumed to be adequately insulated, & there is no heat gain from or heat loss to, the surrounding.

4. The product of Steam rate & the difference of work done between turbine & pump, when the steam rate is expressed in kg/kWh is equal to?
a) 36
b) 60
c) 360
d) 3600

View Answer

Answer: d [Reason:] The steam rate in terms of kg/kWh is given by the expression as, Steam Rate = 3600/(Wt – WP) kg/kWh.

5. The product of cycle efficiency & heat input is given by which of the following relations?
a) Wt – WP
b) Wt x WP
c) Wt / WP
d) none of the mentioned

View Answer

Answer: a [Reason:] The expression for cycle efficiency n is given by the following expression, n = (Wt – WP)/(Q1).

6. What is the effect of increase in regeneration on steam rate?
a) decreases
b) remains same
c) increases
d) none of the mentioned

View Answer

Answer: c [Reason:] More steam has to circulate per hour to produce unit shaft output.

7. What is the relation between efficiencies of Carnot cycle & the ideal Sterling Engine?
a) Both are equal
b) Carnot cycle efficiency > Efficiency of Sterling Engine
c) Carnot cycle efficiency < Efficiency of Sterling Engine
d) No relation between Carnot cycle efficiency & efficiency of Sterling Engine

View Answer

Answer: a [Reason:] All the heat is added reversibly & all the heat is rejected reversibly. Hence, the efficiency of Carnot Cycle is equal to efficiency of Sterling Engine.

8. Heat transfer taking place in the turbine is?
a) from the vapour to the condensate
b) from the condensate to the vapour
c) no heat transfer
d) none of the mentioned

View Answer

Answer: a [Reason:] Following the Stirling cycle, in the ideal regenerative cycle the condensate after leaving the pump circulates around the turbine casing so that heat is transferred from the vapour expanding in the turbine to the condensate circulating around it.

9. The heat transfer taking place in the turbine is?
a) irreversible
b) reversible
c) both of the mentioned
d) none of the mentioned

View Answer

Answer: b [Reason:] At each point the temperature of the vapour is only infinitesimally higher than the temperature of the liquid.

10. The relation between the steam rate of ideal regenerative cycle & steam rate of rankine cycle is?
a) steam rate of ideal regenerative cycle = steam rate of rankine cycle
b) steam rate of ideal regenerative cycle > steam rate of rankine cycle
c) steam rate of ideal regenerative cycle < steam rate of rankine cycle
d) no relation

View Answer

Answer: b [Reason:] Net Work output of the ideal regenerative cycle is less & hence, its steam rate will be more.

Set 4

1. In an ideal regenerative cycle, heat input is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump

View Answer

Answer: a [Reason:] In a regenerative cycle, the heat input is at Boiler (from the flow chart of an ideal regenerative cycle).

2. In an ideal regenerative cycle, heat output is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump

View Answer

Answer: c [Reason:] In a regenerative cycle, the heat output is at the Condenser (from the flow chart of an ideal regenerative cycle).

3. In an ideal regenerative cycle, the work output is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump

View Answer

Answer: b [Reason:] In a regenerative cycle, the work output is at the Condenser (from the flow chart of an ideal regenerative cycle).

4. In an ideal regenerative cycle, the work input is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump

View Answer

Answer: d [Reason:] In a regenerative cycle, the work input is at the Condenser (from the flow chart of an ideal regenerative cycle).

5. What effect does the heating of feedwater by steam ‘bled’ from the turbine has on the Rankine Cycle?
a) it rankinises the Rankine Cycle
b) it carnotinises the Rankine Cycle
c) it reheats the Rankine Cycle
d) none of the mentioned

View Answer

Answer: b [Reason:] The heating of feedwater by steam ‘bled’ from the turbine, known as regeneration, carnotinises the Rankine cycle.

6. What is the effect of increase in regeneration on steam rate?
a) steam rate increases
b) steam rate decreases
c) steam rate isindependent of regeneration
d) none of the mentioned

View Answer

Answer: a [Reason:] More steam has to circulate per hour to produce unit shaft output.

7. If h & h1 are the enthalpies at the inlet & at the exhaust, s & s1 are the enthalpies at the inlet & exhaust, the mean temperature of heat addition, T with regeneration is ?
a) (h + h1)/(s + s1)
b) (h + h1)/(s – s1)
c) (h – h1)/(s + s1)
d) (h – h1)/(s – s1)

View Answer

Answer: d [Reason:] The expression for mean temperature of heat addition is given as, T = (h – h1)/(s – s1).

8. If Q represents the heat input, P represents the heat output; the efficiency n in terms of Q & P is given by?
a) n = QP
b) n = (Q-P)/Q
c) n = (P-Q)/Q
d) n = Q/(Q-P)

View Answer

Answer: b [Reason:] The expression of efficiency in terms of heat input & output is given by, n = (Q-P)/Q.

9. If q represents the work output, r represents the work input, Q represents the heat input, the efficiency n in terms of q & r is given by?
a) n = (q-r)/Q
b) n = ( q+r)/Q
c) n = (qr)/Q
d) n = (qr x qr)/Q

View Answer

Answer: a [Reason:] The efficiency in terms of work input, work output & heat input is given by, n = (q-r)/Q.

10. What is the effect of increase in steam rate on boiler size?
a) boiler size increases
b) boiler size increases
c) boiler size is independent of steam rate
d) none of the mentioned

View Answer

Answer: a [Reason:] Increase in steam rate increases by regeneration, i.e., more steam has to circulate per hour to produce unit shaft output. Hence, it increases boiler size.

Set 5

1. The product of steam rate & network when the steam rate is expressed in kg/kWh is equal to?
a) 36
b) 360
c) 3600
d) 60

View Answer

Answer: c [Reason:] The Steam Rate in terms of kJ/kWh is given by the expression, Steam Rate = (3600/Wnet) kg/kWh.

2. The product of heat rate & efficiency when the heat rate is expressed in kJ/kWh is equal to?
a) 60
b) 36
c) 360
d) 3600

View Answer

Answer: d [Reason:] The heat rate in terms of kJ/kWh is given by the expression, Heat Rate = (3600/n) kJ/kWh where, n = efficiency.

3. What is the effect of reheat pressure on mean temperature of heat addition Tml?
a) Reheat pressure is directly proportional to Tml
b) Reheat pressure is inversely proportional to Tml
c) Reheat pressure is equal to Tml
d) Tml is independent of reheat pressure

View Answer

Answer: a [Reason:] As cycle efficiency is reduced with a decrease in reheat pressure. Hence, the mean temperature of heat addition also decreases.

4. Why is the steam not allowed to expand deep into the two phase region before it is taken to reheating?
a) to control flow rate
b) to control phase change
c) to protect reheat tubes
d) none of the mentioned

View Answer

Answer: c [Reason:] The steam is not allowed to expand deep into the two phase region before it is taken to reheating, because the moisture particles in the steam while evaporating would leave behind solid deposits in the form of scale which is difficult to remove. Hence, when the steam expands, the reheat tubes are damaged.

5. Net Work output of the plant __________ with reheat.
a) decreases
b) increases
c) remains same
d) none of the mentioned

View Answer

Answer: b [Reason:] With reheat, the area under the curve increases in comparison to what it was without reheat. Hence, Net Work output of the plant increases.

6. Which of the following problems are posed by increasing the number of reheats?
a) Cost & Fabrication problems arise
b) Heat transfer problems arise
c) Frictional losses arise
d) None of the mentioned

View Answer

Answer: a [Reason:] Higher the number of Reheats, still higher steam pressures could be used, but mechanical stresses increase at a higher proportion than the increase in pressure, because of the prevailing high temperature. The cost & fabrication difficulties will also increase.

7. What is the effect of decrease of reheat pressure on the quality of steam at turbine exhaust?
a) decreases
b) increases
c) remains same
d) none of the mentioned

View Answer

Answer: b [Reason:] For too low a reheat pressure, the exhaust steam may even be in the superheated state which isn’t good.

8. The optimum reheat pressure for most of the power plants is how many times of the initial steam pressure?
a) 0.1-0.15
b) 0.2-0.20
c) 0.2-0.25
d) 0.1-0.10

View Answer

Answer: c [Reason:] The efficiency increases as the reheat pressure is lowered & reaches a peak at a pressure ratio between 0.2-0.25.

9. What is the most preferable dryness fraction of the exhaust steam?
a) 0.99
b) 0.77
c) 0.66
d) 0.88

View Answer

Answer: d [Reason:] The dryness fraction of the exhaust steam is in the range of 0.86-0.88 for modern turbines.

10. For pressure ratio = 1, efficiency = 0,
a) reheat is used
b) reheat is not used
c) only reheat is used
d) none of the mentioned

View Answer

Answer: b [Reason:] There cannot be any reheat cycle employed when the cycle efficiency is zero and the pressure ratio is equal to 1.