# Mechanical Engineering Thermodynamics – Set 21

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## Q1. The processes occurring in open system which permit the transfer of mass to and from the system, are known as

(A) Flow processes
(B) Non-flow processes
(D) None of these

## Q2. The main cause for the irreversibility is

(A) Mechanical and fluid friction
(B) Unrestricted expansion
(C) Heat transfer with a finite temperature difference
(D) All of the above

Answer: (D) All of the above

## Q3. The measurement of a thermodynamic property known as temperature is based on

(A) Zeroth law of thermodynamics
(B) First law of thermodynamics
(C) Second law of thermodynamics
(D) None of these

Answer: (A) Zeroth law of thermodynamics

## Q4. One kg of carbon monoxide requires 4/7 kg of oxygen and produces

(A) 11/3 kg of carbon dioxide gas
(B) 7/3 kg of carbon monoxide gas
(C) 11/7 kg of carbon dioxide gas
(D) 8/3 kg of carbon monoxide gas

Answer: (C) 11/7 kg of carbon dioxide gas

(A) Kelvin
(B) Joule
(C) Clausis
(D) Gay-Lussac

## Q6. Which of the following statement is wrong?

(A) The closed cycle gas turbine plants are external combustion plants.
(B) In the closed cycle gas turbine, the pressure range depends upon the atmospheric pressure.
(C) The advantage of efficient internal combustion is eliminated as the closed cycle has an external surface.
(D) In open cycle gas turbine, atmosphere acts as a sink and no coolant is required.

Answer: (B) In the closed cycle gas turbine, the pressure range depends upon the atmospheric pressure.

## Q7. The gas constant (R) is equal to the

(A) Sum of two specific heats
(B) Difference of two specific heats
(C) Product of two specific heats
(D) Ratio of two specific heats

Answer:(B) Difference of two specific heats

(A) One
(B) Two
(C) Three
(D) Four

## Q9. The polytropic index (n) is given by

(A) log (p1p2)/log (v1v2)
(B) log (p2/ p1)/log (v1/ v2)
(C) log (v1/ v2)/ log (p1/p2)
(D) log [(p1v1)/(p2v2)]

Answer: (B) log (p2/ p1)/log (v1/ v2)

## Q10. In a steady flow process, the ratio of

(A) Heat transfer is constant
(B) Work transfer is constant
(C) Mass flow at inlet and outlet is same
(D) All of these

## Q11. Diesel cycle consists of __ processes.

(A) Two constant volume and two isentropic
(B) Two constant pressure and two isentropic
(C) Two constant volume and two isothermal
(D) One constant pressure, one constant volume and two isentropic

Answer: (D) One constant pressure, one constant volume and two isentropic

## Q12. When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel, the process is known as __ of fuel.

(A) Atomization
(B) Carbonization
(C) Combustion
(D) None of these

## Q13. The gas in cooling chamber of a closed cycle gas turbine is cooled at

(A) Constant volume
(B) Constant temperature
(C) Constant pressure
(D) None of these

## Q14. Which of the following statement is incorrect?

(A) The liquid fuels consist of hydrocarbons
(B) The liquid fuels have higher calorific value than solid fuels
(C) The solid fuels have higher calorific value than liquid fuels
(D) A good fuel should have low ignition point

Answer: (C) The solid fuels have higher calorific value than liquid fuels

## Q15. Stirling and Ericsson cycles are

(A) Reversible cycles
(B) Irreversible cycles
(C) Semi-reversible cycles
(D) Quasi-static cycles

## Q16. The mass of flue gas per kg of fuel is the ratio of the

(A) Mass of oxygen in 1 kg of flue gas to the mass of oxygen in 1 kg of fuel
(B) Mass of oxygen in 1 kg of fuel to the mass of oxygen in 1 kg of flue gas
(C) Mass of carbon in 1 kg of flue gas to the mass of carbon in 1 kg of fuel
(D) Mass of carbon in 1 kg of fuel to the mass of carbon in 1 kg of flue gas

Answer: (C) Mass of carbon in 1 kg of flue gas to the mass of carbon in 1 kg of fuel

## Q17. Which is the incorrect statement about Carnot cycle?

(A) It is used as the alternate standard of comparison of all heat engines.
(B) All the heat engines are based on Carnot cycle.
(C) It provides concept of maximizing work output between the two temperature limits.
(D) All of the above

Answer: (B) All the heat engines are based on Carnot cycle.

## Q18. Petrol is distilled at

(A) 65° to 220°C
(B) 220° to 345°C
(C) 345° to 470°C
(D) 470° to 550°C

(A) Element
(B) Compound
(C) Atom
(D) Molecule