Top 50+ Solved Combustion in SI and SI Engines MCQ Questions Answer
Q. Crankcase explosion in I.C. engines usually occurs as
a. first a mild explosion followed by a bi explosion
b. first a big explosion followed by a mil explosion
c. both mild and big explosions occi simultaneously
d. never occurs
Q. Compression loss in I.C engines occurs duto
a. leaking piston rings
b. use of thick head gasket
c. clogged air-inlet slots
d. all of the above.
Q. It the temperature of intake air in IC engines is lowered, then its efficiency will
a. increase
b. decrease
c. remain same
d. increase upto certain limit and then decrease
Q. The precess of breaking up or a liquid into fine droplets by spraying is called
a. vaporisation
b. carburetion
c. ionisation
d. atomisation.
Q. As a result of detonation in an I.C. engine, following parameter attains very high value
a. peak pressure
b. rate of rise of pressure
c. rate of rise of temperature
d. peak temperature
Q. Which of the following statements is correct?
a. All the irreversible engines have same efficiency
b. All the reversible engines have same efficiency
c. Both Rankine and Caront cycles have same efficiency between same temperature limits
d. All reversible engines working between same temperature limits have same-efficiency
Q. The accumulation of carbon in a cylinder results in increase of
a. clearance volume
b. volumetric efficiency
c. ignition time
d. effective compression ratio
Q. In diesel engine the diesel fuel injected intc cylinder would burn instantly at about compressed air temperature of
a. 250°C
b. 500°C
c. 1000°C
d. 150CPC
Q. Excess quantities of sulphur in diesel fuel are Objectionable because it may cause thefollowing
a. piston ring and cylinder wear
b. formation of hard coating on piston skirts
c. oil sludge in the engine crank case
d. detonation
Q. Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows
a. using additives in the fuel
b. engine derating i.e. reducing the maxi-mum flow of fuel
c. increasing the compression ratio
d. adherence to proper fuel specification
Q. A high flame speed is obtained in diesel engine when air fuel ratio is
a. uniform throughout the mixture
b. chemically correct mixture
c. about 3-5% rich mixture
d. about 10% rich mixture
Q. The knock in diesel engine occurs due to
a. instantaneous and rapid burning of the first part of the charge
b. instantaneous atuo iginition of last part of charge
c. delayed burning of the first part of the charge
d. reduction of delay period
Q. A stoichiometric air-fuel ratio is
a. chemically correct mixture
b. lean mixture
c. rich mixture for idling
d. rich mixture for over loads