I.C Engines Objective Questions with Answers – Set 12

Are you guys looking for Mechanical Engineering MCQ Questions with Answers PDF Free Download as per Mechanical Engineering new exam pattern? You came to the right page. This may assist you to understand and check your knowledge about the Subjects. Students also can take a free test of the Multiple Choice Questions of Mechanical Engineering. Each question has four options followed by the right answer. These Mechanical Engineering MCQ Questions are selected supported by the newest exam pattern.


Q1. The voltage required to produce a spark across the gap, between the sparking points is

(A) 2000 to 4000 volts
(B) 4000 to 6000 volts
(C) 6000 to 10,000 volts
(D) 10,000 to 12,000 volts

Answer: (C) 6000 to 10,000 volts


Q2. The working pressure and temperature inside the cylinder of an internal combustion engine is _ as compared to a steam engine.

(A) Low
(B) Very low
(C) High
(D) Very high

Answer: (D) Very high


Q3. The pressure at the end of compression in the case of diesel engine is of the order of

(A) 6 kg/cm
(B) 12 kg/cm
(C) 20 kg/cm
(D) 35 kg/cm

Answer: (D) 35 kg/cm


Q4. The minimum cranking speed in case of petrol engine is about

(A) Half the operating speed
(B) One fourth of operating speed
(C) 250 – 300 rpm
(D) 60 – 80 rpm

Answer: (D) 60 – 80 rpm


Q5. If V₁ is the jet velocity and V₀ is the vehicle velocity, then the propulsive efficiency of a rocket is given by

(A) [2(V₀/V₁)]/ [1 + (V₀/V₁)²]
(B) (V₀/V₁)/ [1 + (V₀/V₁)²]
(C) V₀/(V₀ + V₁)
(D) V₁/(V₀ + V₁)

Answer: (A) [2(V₀/V₁)]/ [1 + (V₀/V₁)²]


Q6. If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be

(A) 2%
(B) 4%
(C) 8%
(D) 14%

Answer: (D) 14%


Q7. 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

Answer: (C) Increasing the pressure of intake air


Q8. In a typical medium speed 4-stroke cycle diesel engine

(A) Compression starts at 35° after bottom dead center and ends at top dead center
(B) Compression starts at bottom dead center and ends at top dead center
(C) Compression starts at 10° before bottom dead center and, ends just before top dead center
(D) May start and end anywhere

Answer:(A) Compression starts at 35° after bottom dead center and ends at top dead center


Q9. In a four stroke cycle engine, the sequence of operations is

(A) Suction, compression, expansion and exhaust
(B) Suction, expansion, compression and exhaust
(C) Expansion, compression, suction and exhaust
(D) Compression, expansion, suction and exhaust

Answer: (A) Suction, compression, expansion and exhaust


Q10. The magneto in an automobile is basically

(A) Transformer
(B) D.C. generator
(C) Capacitor
(D) Magnetic circuit

Answer: (B) D.C. generator


Q11. The mechanical efficiency (ηm) of the engine is given by

(A) ηm = B.P/I.P
(B) ηm = I.P/B.P
(C) ηm = (B.P × I.P)/100
(D) None of these

Answer:(A) ηm = B.P/I.P


Q12. The calorific value of gaseous fuels is expressed in terms of

(A) kcal
(B) kcal/kg
(C) kcal/m²
(D) kcal/m3

Answer: (D) kcal/m3


Q13. The self ignition temperature of petrol is _ as compared to diesel oil.

(A) Same
(B) Lower
(C) Higher
(D) None of these

Answer: (C) Higher


Q14. Most high speed compression engines operate on

(A) Otto cycle
(B) Diesel cycle
(C) Dual cycle
(D) Carnot cycle

Answer: (C) Dual cycle


Q15. A diesel engine has compression ratio from

(A) 6 to 10
(B) 10 to 15
(C) 15 to 25
(D) 25 to 40

Answer: (C) 15 to 25


Q16. 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

Answer: (C) Bigger than


Q17. The cetane number of diesel oil, generally available, is

(A) 20 to 25
(B) 25 to 30
(C) 30 to 40
(D) 40 to 55

Answer: (D) 40 to 55


Q18. The rating of a diesel engine, with increase in air inlet temperature, will

(A) Increase linearly
(B) Decrease linearly
(C) Increase parabolically
(D) Decrease parabolically

Answer: (B) Decrease linearly


Q19. The fuels in order of decreasing knock tendency for spark ignition engines are

(A) Paraffin, aromatic, napthene
(B) Paraffin, napthene, aromatic
(C) Napthene, aromatics, paraffin
(D) Napthene, paraffin, aromatic

Answer: (B) Paraffin, napthene, aromatic


Q20. Number of working strokes per min. for a two stroke cycle engine is _ the speed of the engine in r.p.m.

(A) Equal to
(B) One-half
(C) Twice
(D) Four-times

Answer:(A) Equal to


We hope the given Mechanical Engineering MCQ Questions with Answers will definitely yield fruitful results. Hope you got enough ideas on the MCQs on Mechanical Engineering. If you have any queries related to Mechanical Engineering MCQs Multiple Choice Questions with Answers, drop your questions below and will get back to you in no time.