Multiple choice question for engineering
Set 1
1. For best results of efficient combustion, high speed diesel engines need an approximate cetane number of
a) 100
b) 10
c) 50
d) 5
Answer
Answer: c
2. Calorific value of diesel oil is of the order of
a) 3000 kcal/kg
b) 5000 kcal/kg
c) 7500 kcal/kg
d) 10000 kcal/kg
Answer
Answer: d
3. Carbon residue in diesel oil should not be more than
a) 1%
b) 0.5%
c) 0.1%
d) 0.01%
Answer
Answer: c
4. The most popular firing order in case of four cylinder in-line I.C. engine is
a) 1-2-3-4
b) 1-3-2-4
c) 1-4-2-3
d) 1-3-4-2
Answer
Answer: d
5. The compression ratio of motor cars is
a) 5
b) 7
c) 10
d) 13
Answer
Answer: b
6. The specific gravity of diesel oil is
a) 1
b) 0.7
c) 0.85
d) 0.5
Answer
Answer: c
7. Freezing temperature of petrol is about
a) 0.65
b) 0.75
c) 0.85
d) 0.95
Answer
Answer: b
8. Choose the correct statement, detonation can be controlled by
a) varying compression ratio
b) using lean mixture
c) retarding the spark timing
d) reducing the r.p.m
Answer
Answer: c [Reason:] Detonation can be controlled by retarding the spark timing.
9. The efficiency of I.C. engines normally is of the order of
a) 15-20%
b) 20-25%
c) 25-30%
d) 30-35%
Answer
Answer: d
10. The firing order of a six stroke I.C. engine is
a) 1-3-6-5-2-4
b) 1-4-2-5-6-3
c) 1-6-2-5-4-3
d) 1-5-3-4-2-6
Answer
Answer: d [Reason:] The firing order of a six stroke I.C. engine is 1-5-3-4-2-6 and firing order in case of four cylinder in-line I.C. engine is 1-3-4-2.
11. Sulphur content in diesel engine oil should not be more than
a) 10%
b) 5%
c) 1%
d) 0.1%
Answer
Answer: c
12. The ash content in diesel oil should be not be more than
a) 1%
b) 5%
c) 0.1%
d) 0.01%
Answer
Answer: d [Reason:] The ash content in diesel oil should be not be more than 0.01% while sulphur content in diesel engine oil should not be more than 1%.
Set 2
1. The process of clearing the cylinder after the expansion stroke is called scavenging process.
a) True
b) False
Answer
Answer: a [Reason:] Scavenging process is defined as the process of clearing the cylinder after the expansion stroke.
2. Scavenging process is the replacement of combustion products in the cylinder from previous power stroke with fresh air charge to be burned in the next cycle.
a) True
b) False
Answer
Answer: a
3. The efficiency of a two stroke engine does not depends on the effectiveness of the scavenging process.
a) True
b) False
Answer
Answer: b [Reason:] Actually, the efficiency of a two stroke engine greatly depends on the effectiveness of the scavenging process.
4. Inadequate scavenging leads to high mean indicated pressure which results in high weight and high cost per kW for the engine.
a) True
b) False
Answer
Answer: b [Reason:] In fact, inadequate scavenging leads to low mean indicated pressure which results in high weight and high cost per kW for the engine.
5. Inadequate scavenging leads to low amount of oxygen availability which results in incomplete combustion leading to higher specific fuel combustion.
a) True
b) False
Answer
Answer: a
6. Inadequate scavenging leads to contamination of lubricating oil to a greater extent which reduces the lubricating qualities and eventually results in increased wear of piston and cylinder liners.
a) True
b) False
Answer
Answer: a
7. Scavenging angle is the crank angle during which both inlet and exhaust port are open.
a) True
b) False
Answer
Answer: a
8. Scavenging period is the time period taken for crank angle.
a) True
b) False
Answer
Answer: b [Reason:] In fact, scavenging period is the time period taken for scavenging angle.
9. The theoretical scavenging processes are
a) perfect scavenging
b) perfect mixing
c) short circuiting
d) all of the mentioned
Answer
Answer: d [Reason:] The theoretical scavenging processes are
a) perfect scavenging
b) perfect mixing
c) short circuiting.
10. In short circuiting process, the fresh charge coming from the scavenge manifold directly goes out of the exhaust ports without removing combustion products.
a) True
b) False
Answer
Answer: a
Set 3
1. The Stirling cycle consists of
a) two isothermal and two constant pressure processes
b) two isothermal and two constant volume processes
c) two isothermal and two adiabatic processes
d) none of the mentioned
Answer
Answer: b
2. In a Stirling cycle, the heat rejection and addition takes place at constant
a) pressure
b) volume
c) temperature
d) none of the mentioned
Answer
Answer: c
3. If Stirling cycle with regenerative arrangement and Carnot cycle operate within same temperature limits, then the thermal efficiency of Carnot cycle will be
a) same
b) half
c) twice
d) none of the mentioned
Answer
Answer: a
4. The Ericsson cycle consists of
a) two isothermal and two constant pressure processes
b) two isothermal and two constant volume processes
c) two isothermal and two adiabatic processes
d) none of the mentioned
Answer
Answer: a [Reason:] The Ericsson cycle consists of two isothermal and two constant pressure processes while the Stirling cycle consists of two isothermal and two constant volume processes.
5. Stirling and Ericsson cycles are
a) reversible cycles
b) irreversible cycles
c) quasi-static cycles
d) semi-reversible cycles
Answer
Answer: a
6. The efficiency of Stirling cycle is _____________ Carnot cycle.
a) greater than
b) less than
c) equal to
d) none of the mentioned
Answer
Answer: c
7. The concept of regeneration is used in following cycles
a) Rankine and Stirling
b) Rankine and Ericsson
c) Ericsson and Stirling
d) None of the mentioned
Answer
Answer: c
8. The efficiency of Ericsson cycle is ___________ Carnot cycle.
a) greater than
b) less than
c) equal to
d) none of the mentioned
Answer
Answer: c
9. Both the Ericsson cycle and Joule’s cycle have two constant pressure processes.
a) True
b) False
Answer
Answer: a
Set 4
1. Which of the following statement is not correct with respect to alcohols as alternate fuel in IC engines
a) anti-knock characteristics of alcohol is poor
b) alcohol contains about half the heat energy of gasoline/litre
c) alcohol does not vaporize as easily as gasoline
d) alcohols are corrosive in nature
Answer
Answer: a [Reason:] Anti-knock characteristics of alcohol is good.
2. Gasohol is a mixture of
a) 90% ethanol + 10% gasoline
b) 10% ethanol + 90% gasoline
c) 40% ethanol + 60% gasoline
d) 50% ethanol + 50% gasoline
Answer
Answer: b [Reason:] 10% ethanol + 90% gasoline makes gashol.
3. Stoichiometric air-fuel ratio of alcohol when compared to gasoline is
a) higher
b) lower
c) equal
d) none of the mentioned
Answer
Answer: b
4. Small amount of gasoline is added to alcohol to
a) reduce the emission
b) to increase the power output
c) to increase the efficiency
d) to improve cold weather starting
Answer
Answer: d
5. Methanol by itself is not a good CI engine fuel because
a) its octane number is high
b) its cetane number is low
c) all of the mentioned
d) none of the mentioned
Answer
Answer: c
6. Anti-knock characteristics of alcohol when compared to gasoline is
a) higher
b) lower
c) equal
d) none of the mentioned
Answer
Answer: a [Reason:] Anti-knock characteristics of alcohol when compared to gasoline is higher and stoichiometric air-fuel ratio of alcohol when compared to gasoline is generally lower.
7. Alcohols alone cannot be used in CI engines as
a) their self ignition temperature is high
b) latent heat of vaporization is high
c) all of the mentioned
d) none of the mentioned
Answer
Answer: c
8. The compression ratio of alcohol fuel lies between
a) 11:1 to 13:1
b) 7:1 to 9:1
c) 5:1 to 7:1
d) none of the mentioned
Answer
Answer: a
9. The calorific value of alcohols is _____________ in diesel oil.
a) higher than
b) lower than
c) same
d) none of the mentioned
Answer
Answer: b
10. The effective inhibitor of pre-ignition is
a) alcohol
b) water
c) lead
d) none of the mentioned
Answer
Answer: b [Reason:] The effective inhibitor of pre-ignition is water and not alcohol or lead.
Set 5
1. An SI engine sometimes continues to run for a very small period even after the ignition is switched off. This phenomenon is called
a) idling
b) dieseling
c) throttling
d) none of the mentioned
Answer
Answer: b [Reason:] Dieseling is the phenomenon in which an SI engine sometimes continues to run for a very small period even after the ignition is switched off.
2. Dieseling may take place due to
a) engine idling speed set to high
b) increase in compression ratio due to carbon deposits
c) inadequate or low octane rating
d) all of the mentioned
Answer
Answer: d [Reason:] Dieseling may take place due to engine idling speed set to high, increase in compression ratio due to carbon deposits, inadequate or low octane rating, engine overheating, too high spark plug heat range, incorrect adjustment of idle fuel-air mixture, sticking of throttle, requirement of tune up of engine and oil entry into the cylinder.
3. Dieseling may take place due to
a) engine overheating
b) too high spark plug heat range
c) incorrect adjustment of idle fuel-air mixture
d) all of the mentioned
Answer
Answer: d [Reason:] Dieseling may take place due to engine idling speed set to high, increase in compression ratio due to carbon deposits, inadequate or low octane rating, engine overheating, too high spark plug heat range, incorrect adjustment of idle fuel-air mixture, sticking of throttle, requirement of tune up of engine and oil entry into the cylinder.
4. Dieseling may take place due to
a) sticking of throttle
b) requirement of tune up of engine and oil entry into the cylinder
c) none of the mentioned
d) all of the mentioned
Answer
Answer: d [Reason:] Dieseling may take place due to engine idling speed set to high, increase in compression ratio due to carbon deposits, inadequate or low octane rating, engine overheating, too high spark plug heat range, incorrect adjustment of idle fuel-air mixture, sticking of throttle, requirement of tune up of engine and oil entry into the cylinder.
5. The solenoid valve operated idling circuit reduces
a) engine performance
b) hydrocarbon emissions
c) CO emissions
d) none of the mentioned
Answer
Answer: b
6. In order to accelerate the vehicle and consequently its engine, the mixture required is very
a) rich
b) lean
c) thin
d) none of the mentioned
Answer
Answer: a [Reason:] Generally, in order to accelerate the vehicle and consequently its engine, the mixture required is very rich.
7. An economizer valve opens at ______________ throttle operation.
a) half
b) full
c) partial
d) none of the mentioned
Answer
Answer: b [Reason:] An economizer valve, generally opens at full throttle operation.
8. Economizer is also known as
a) power enrichment system
b) power less system
c) power throttle system
d) none of the mentioned
Answer
Answer: a [Reason:] Another name for economizer is power enrichment system.
9. Economizer allows a large opening to the main jet when the throttle is ____________ beyond a specified limit.
a) closed
b) opened
c) partially opened
d) none of the mentioned
Answer
Answer: b
10. The metering rod used in an economizer
a) is tapered
b) is not tapered
c) may be tapered
d) none of the mentioned
Answer
Answer: c
