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This set of Engineering Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Engineering Thermodynamics Set 13
Q1 | Example of reversed heat engine is
- heat pump
- refrigerator
- both of the mentioned
- none of the mentioned
Q2 | Efficiency of a reversible heat engine is given by
- 1-(t1/t2)
- 1-(t2/t1)
- (t1/t2)-1
- (t2/t1)-1
Q3 | For a reversible refrigerator, Coefficient of Performance is given by
- t2/(t1-t2)
- t1/(t1-t2)
- t2/(t2-t1)
- t1/(t2-t1)
Q4 | Entropy principle is the quantitative statement of the second law of thermodynamics.
- true
- false
Q5 | Which of the following can be considered as an application of entropy principle?
- transfer of heat through a finite temperature difference
- mixing of two fluids
- maximum temperature obtainable from two finite bodies
- all of the mentioned
Q6 | The final temperatures of two bodies, initially at T1 and T2 can range from
- (t1-t2)/2 to sqrt(t1*t2)
- (t1+t2)/2 to sqrt(t1*t2)
- (t1+t2)/2 to (t1*t2) d) (t1-t2)/2 to (t1*t2)
Q7 | Which of the following processes exhibit external mechanical irreversibility?
- isothermal dissipation of work
- adiabatic dissipation of work
- both of the mentioned
- none of the mentioned
Q8 | Which of the following is an example of low grade energy?
- heat or thermal energy
- heat from nuclear fission or fusion
- heat from combustion of fossil fuel
- all of the mentioned
Q9 | Which of the following is an example of high grade energy?
- mechanical work
- electrical energy
- water power and wind power
- all of the mentioned
Q10 | The unavailable energy is the product of the lowest temperature of heat rejection and the change of entropy of system during the process of supplying heat.
- true
- false
Q11 | The lowest practicable temperature of heat rejected is the
- given temperature
- 0k
- temperature of surroundings
- 273k
Q12 | Exergy is lost due to
- irreversible heat transfer
- through finite temperature difference
- during the process of heat addition
- all of the mentioned
Q13 | Which of the following is a type of energy?
- high grade energy
- low grade energy
- both of the mentioned
- none of the mentioned
Q14 | The complete conversion of heat into shaft- work is impossible.
- true
- false
Q15 | Energy is said to be degraded each time it flows through a finite temperature difference.
- true
- false
Q16 | When considering a finite energy source, its working fluid expands,
- reversibly
- adiabatically
- reversibly and adiabatically
- none of the mentioned
Q17 | The entropy of any closed system can increase in which if the following way?
- by heat interaction in which there is entropy transfer
- dissipative effects or internal irreversibilities
- both of the mentioned
- none of the mentioned
Q18 | The entropy increase due to internal irreversibility is also called entropy production or entropy generation.
- true
- false
Q19 | Which of the following statement is true?
- if the isentropic process is reversible, it must be adiabatic
- if the isentropic process is adiabatic, it cannot but be reversible
- if the process is adiabatic and reversible, it must be isentropic
- all of the mentioned
Q20 | Lost work is given by
- pdv-dw
- pdv+dw
- -pdv-dw
- pdv*dw
Q21 | Which of the following statement is false?
- for a reversible process, entropy generation is zero
- the entropy generation does not depend on the path the system follows
- for an irreversible process, entropy generation is greater than zero
- none of the mentioned
Q22 | Mass and energy are conserved quantities, but entropy is generally not conserved.
- true
- false
Q23 | A chip dissipates 2 kJ of electric work and rejects it as heat transfer from its surface which is at 50°C to 25°C air. How much entropy is generated outside the chip?
- 0.419 j/k
- 0.519 j/k
- 0.619 j/k
- 0.719 j/k
Q24 | Entropy increase dS of the system can be expressed as
- ds=ds(due to external heat interaction)- ds(due to internal irreversibility)
- ds=ds(due to external heat interaction)+ds(due to internal irreversibility)
- ds=-ds(due to external heat interaction)- ds(due to internal irreversibility)
- ds=-ds(due to external heat interaction)+ds(due to internal irreversibility)
Q25 | If the path A causes more entropy generation than path B, then
- path a is more irreversible than path b
- path a involves more lost work
- both of the mentioned
- none of the mentioned