I.C Engines Objective Questions with Answers – Set 03

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Q1. During idling, a petrol engine requires _ mixture.

(A) Lean
(B) Rich
(C) Chemically correct
(D) None of these

Answer: (B) Rich


Q2. All heat engines utilize

(A) Low heat value of oil
(B) High heat value of oil
(C) Net calorific value of oil
(D) Calorific value of fuel

Answer: (A) Low heat value of oil


Q3. The volumetric efficiency of a well designed engine may be

(A) 30 to 40%
(B) 40 to 60%
(C) 60 to 70%
(D) 75 to 90%

Answer: (D) 75 to 90%


Q4. An hmh flame speed is obtained in diesel engine when air fuel ratio is

(A) Uniform throughout the mixture
(B) Chemically correct mixture
(C) About 35% of rich mixture
(D) About 10% of rich mixture

Answer: (D) About 10% of rich mixture


Q5. The sensing element in the control system of nuclear reactors measures the _ of the neutron flux in the reactor.

(A) Temperature
(B) Volume
(C) Density
(D) None of these

Answer: (C) Density


Q6. Supercharging is essential in

(A) Diesel engines
(B) Gas turbines
(C) Petrol engines
(D) Aircraft engines

Answer:(D) Aircraft engines


Q7. In a petrol engine, if diesel is used, then the engine will

(A) Not run
(B) Run more efficiently
(C) Run at high speed
(D) Explode

Answer: (A) Not run


Q8. In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the

(A) Beginning of suction stroke
(B) End of suction stroke
(C) Beginning of exhaust stroke
(D) End of exhaust stroke

Answer: (A) Beginning of suction stroke


Q9. The thermodynamic cycle on which the petrol engine works, is

(A) Otto cycle
(B) Joule cycle
(C) Rankine cycle
(D) Stirling cycle

Answer: (A) Otto cycle


Q10. Alpha-methyl-naphthalene (C₁₁ H₁₀) has a cetane number of

(A) 0
(B) 50
(C) 100
(D) 120

Answer: (A) 0


Q11. The knocking in diesel engines may be prevented by

(A) Reducing the delay period
(B) Raising the compression ratio
(C) Increasing the inlet pressure of air
(D) All of these

Answer: (D) All of these


Q12. The air standard efficiency of an I.C. engine is given by (where r = Compression ratio, and γ = Ratio of specific heats)

(A) 1 – rγ – 1
(B) 1 + rγ – 1
(C) 1 – (1/rγ – 1)
(D) None of these

Answer: (C) 1 – (1/rγ – 1)


Q13. The mean effective pressure obtained from engine indicator indicates the

(A) Maximum pressure developed
(B) Minimum pressure
(C) Instantaneous pressure at any instant
(D) Average pressure

Answer: (D) Average pressure


Q14. It the temperature of intake air in IC engines is lowered, then its efficiency will

(A) Increase
(B) Decrease
(C) Remain same
(D) Increase up to certain limit and then decrease

Answer: (A) Increase


Q15. A supercharged engine as compared to an ordinary engine

(A) Requires smaller foundation
(B) Is lighter
(C) Consumes less lubricating oil
(D) All of these

Answer: (D) All of these


Q16. Volatility of diesel fuel oil is

(A) Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
(B) Temperature at which it solidifies or congeals
(C) It catches fire without external aid
(D) Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off

Answer: (D) Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off


Q17. 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

Answer: (C) Spark plug


Q18. The air-fuel ratio in petrol engines is controlled by

(A) Controlling valve opening/closing
(B) Governing
(C) Injection
(D) Carburetion

Answer: (D) Carburetion


Q19. Which of the following statement is wrong?

(A) A four stroke cycle engine develops twice the power as that of a two stroke cycle engine
(B) For the same power developed, a four stroke cycle engine is lighter, less bulky and occupies less floor area
(C) The petrol engines are costly than diesel engines
(D) All of the above

Answer: (D) All of the above


Q20. A 5 BHP engine running at full load would consume diesel of the order of

(A) 0.3 kg/hr
(B) 1 kg/hr
(C) 3 kg/hr
(D) 5 kg/hr

Answer:(B) 1 kg/hr


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