# I.C Engines Objective Questions with Answers – Set 12

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## 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

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

(A) 6 kg/cm
(B) 12 kg/cm
(C) 20 kg/cm
(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]

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

## 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

## 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

(A) kcal
(B) kcal/kg
(C) kcal/m²
(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

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

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

## 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

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

## 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