IC engine practice exam - Set 15 - ObjectiveBooks

# Practice Test: Question Set - 15

1. The ratio of the brake power to the indicated power is called
(A) Mechanical efficiency
(B) Overall efficiency
(C) Indicated thermal efficiency
(D) Volumetric efficiency

2. The cetane (C₁₆H₃₄) which is a straight chain paraffin, is assigned a cetane number of
(A) 0
(B) 50
(C) 100
(D) 120

3. The thermodynamic cycle on which the petrol engine works, is
(A) Otto cycle
(B) Joule cycle
(C) Rankine cycle
(D) Stirling cycle

4. The correct mixture strength (by weight) for petrol is about
(A) 14.6 : 1
(B) 18.5 : 1
(C) 20.4 : 1
(D) 22.6 : 1

5. The scavenging efficiency of a four stroke cycle diesel engine is
(A) Below 50%
(B) Between 50 and 85%
(C) Between 85 and 95%
(D) Between 95 and 100%

6. If the speed of the engine is increased, the indicated power will
(A) Increase
(B) Decrease
(C) Remain same
(D) None of these

7. The specific fuel consumption per B.P. hour for a petrol engine is about
(A) 0.2 kg
(B) 0.25 kg
(C) 0.3 kg
(D) 0.35 kg

8. The injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to
(A) Inject fuel in a chamber of high pressure at the end of compression stroke
(B) Inject fuel at a high velocity to facilitate atomization
(C) Ensure that penetration is not high
(D) All of the above

9. A fuel of cetane number 40 has the same ignition quality as a mixture of
(A) 40% cetane and 60% alpha methyl naphthalene
(B) 40% alpha methyl naphthalene and 60% cetane
(C) 40% petrol and 60% diesel
(D) 40% diesel and 60% petrol

10. The two reference fuels used for cetane rating are
(A) Cetane and iso-octane
(B) Cetane and alpha-methyl naphthalene
(C) Cetane and normal heptane
(D) Cetane and tetra ethyl lead

11. In petrol engines, the delay period is of the order of
(A) 0.001 second
(B) 0.002 second
(C) 0.003 second
(D) 0.004 second

12. A diesel engine is _________ as compared to petrol engine, both running at rated load.
(A) Equally efficient
(B) Less efficient
(C) More efficient
(D) None of these

13. The pressure at the end of compression, in petrol engines, is approximately
(A) 10 bar
(B) 20 bar
(C) 25 bar
(D) 35 bar

14. The turbine of the turboprop engine is __________ that of the turbojet engine.
(A) Same as
(B) Smaller than
(C) Bigger than
(D) None of these

15. A higher compression ratio causes
(A) Pre-ignition
(B) Increase in detonation
(C) Acceleration in the rate of combustion
(D) Any one of these

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