Internal Combustion Engines - Set 06 - ObjectiveBooks

Internal Combustion Engines - Set 06

Practice Test: Question Set - 06

1. When crude oil is heated, then which of the following hydrocarbon is given off first?
    (A) Kerosene
    (B) Gasoline
    (C) Paraffin
    (D) Natural gas

2. Supercharging is the process of supplying the intake air to the engine cylinder at a density _________ the density of the surrounding atmosphere.
    (A) Equal to
    (B) Less than
    (C) Greater than
    (D) None of these

3. Polymerization is a chemical process in which molecules of a compound become
    (A) Larger
    (B) Slowed down
    (C) Smaller
    (D) Liquid

4. In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
    (A) Fuel pump
    (B) Fuel injector
    (C) Spark plug
    (D) None of these

5. For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of
    (A) 9 : 1
    (B) 12 : 1
    (C) 15 : 1
    (D) 18 : 1

6. The ratio of the indicated thermal efficiency to the air standard efficiency is known as
    (A) Mechanical efficiency
    (B) Overall efficiency
    (C) Volumetric efficiency
    (D) Relative efficiency

7. The knock in diesel engine occurs due to
    (A) Instantaneous and rapid burning of the first part of the charge
    (B) Instantaneous auto ignition of last part of charge
    (C) Delayed burning of the first part of the charge
    (D) Reduction of delay period

8. Which of the following statement is correct regarding petrol engines?
    (A) A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure
    (B) The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug
    (C) The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition
    (D) All of the above

9. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the
    (A) Exhaust will be smoky
    (B) Piston rings would stick into piston grooves
    (C) Engine starts overheating
    (D) Scavenging occurs

10. Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to
    (A) Cylinder walls being too hot
    (B) Overheated spark plug points
    (C) Red hot carbon deposits on cylinder walls
    (D) Any one of these

11. Scavenging air in diesel engine means
    (A) Air used for combustion sent under pressure
    (B) Forced air for cooling cylinder
    (C) Burnt air containing products of combustion
    (D) Air used for forcing burnt gases out of engine's cylinder during the exhaust period

12. The reference fuels for knock rating of spark ignition engines would include
    (A) Iso-octane and alpha-methyl naphthalene
    (B) Normal octane and aniline
    (C) Iso-octane and normal hexane
    (D) Normal heptane and iso-octane

13. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft
    (A) 1/2
    (B) 1
    (C) 2
    (D) 4

14. The brake power of a diesel engine, keeping other parameters constant, can be increased by
    (A) Decreasing the density of intake air
    (B) Increasing the temperature of intake air
    (C) Increasing the pressure of intake air
    (D) Decreasing the pressure of intake air

15. Engine pistons are usually made of aluminium alloy because it
    (A) Is lighter
    (B) Wear is less
    (C) Absorbs shocks
    (D) Is stronger

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