Top 350+ Solved Heat Engines MCQ Questions Answer
Q. Octane number of petrol generally available is in the range
a. 10 to 25
b. 55 to 65
c. 25 to 60
d. 20 to 75
e. 80 to 100
Q. In spark ignition engines, the knocking tendency is reduced by
a. Reduction of compression ratio
b. Advancing ignition timing
c. Increasing exhaust temperature
d. Adding dope like tetra ethy lead to the fuel
e. All of the above
Q. In thermodynamic analysis, a pure substance is that which
a. consists of only a single chemical species
b. May have a number of chemical species that the composition remains constant
c. has no dissolved impurities
d. behaves as perfect gas
e. None of the above
Q. Leaking radiator tubes are generally
a. Soldered
b. Welded
c. Left unattended
d. Brazed
e. Replaced
Q. When steam expands without doing mechanical work, its enthalpy
a. Increases
b. Decreases
c. Does not change
d. Depends on the factors
e. None of the above
Q. Generally steam turbines in power station operate at
a. 1000 RPM
b. 3000 RPM
c. 375 RPM
d. 50 RPM
e. 1500 RPM
Q. Thermionic converters are based on
a. Seebeck effect
b. Microwave theory
c. Energy contained in thermal conductors
d. Transfer of electrons
e. None of the above
Q. Anthydrous substance is
a. Dry substance
b. Free of hydrogen
c. Free of humidity
d. Crystalline substance
e. Free of water specially water of crystallization
Q. In compression ignition engine fuel ignition accelerators are added to
a. Reduce combustion knock
b. Accelerate combustion knock
c. Reduce combustion chamber temp
d. Increase delay period
e. None of the above
Q. Working pressure of a boiler does not depend upon
a. Factor of safety
b. Tensile strength of shell
c. Thickness of shell
d. Efficiency of joint
e. Type of fuel being fired
Q. Oil rings are slotted to
a. Remove oil from cylinder
b. Minimise friction
c. Reduce the bulk
d. Better lubrication of cylinder walls
e. Provide an escape for the oil that the slot edges cut from the cylinder wall
Q. A gas turbine cycle operates through pressures ratio of 5. Air enters the compressor at atmospheric pressure and 25?C and entry to the turbine is at 800?C. The thermal efficiency of the plant has been found to be 37%. Now, if compressor and turbine efficiencies of 80% are taken into account, the value, of thermal efficiency will be
a. 37%
b. 40%
c. 38.50%
d. 17.75%
e. 45%
Q. The chemical usually added for increasing the knock resistance of a petrol engine is
a. Tetra-ethy lead
b. n-heptane
c. Pyro gallic acid
d. Methyl alcohol
e. Benzol
Q. Pure cetane
a. Has cetane number of 0
b. Promotes detonation
c. Is a straight chain paraffin
d. Has cetane number of 100
e. Is a blue coloured liquid