# Thermal Engineering 10

Objective Questions and Answer: Thermal Engineering 10

Subject: Thermal Engineering 10

Part 10: Objective questions and answers of Thermal Engineering

Q1. Carnot cycle has maximum efficiency for

a) Reversible engine

b) Irreversible engine

c) New engine

d) Petrol engine

Q2. Measurement of temperature is based on

a) Thermodynamic properties

b) Zeroth law of thermodynamics

c) First law of thermodynamics

d) Second law of thermodynamics

Q3. Carnot cycle efficiency depends upon

a) Properties of the medium/substance used

b) Condition of engine

c) Working condition

d) Temperature range of operation

Q4. Carnot cycle efficiency is maximum when

a) Initial temperature is 0°K

b) Final temperature is 0°K

c) Difference between initial and final temperature is 0°K

d) Final temperature is 0°C

Q5. An engine operates between temperatures of 900°K and r2 and another engine between T2 and 400°K For both to do equal work, value of T2 will be

a) 650°K

b) 600°K

c) 625°K

d) 700°K

Q6. If heat be exchanged in a reversible manner, which of the following property of the working substance will change accordingly

a) Temperature

b) Enthalpy

c) Internal energy

d) Entropy

Q7. If a system after undergoing a series of processes, returns to the initial state then

a) Process is thermodynamically in equilibrium

b) Process is executed in closed system cycle

c) Its entropy will change due to irreversibility

d) Sum of heat and work transfer will be zero

Q8. In an isothermal process, the internal energy of gas molecules

a) Increases

b) Decreases

c) Remains constant

d) May increase/decrease depending on the properties of gas

Q9. An actual engine is to be designed having same efficiency as the Carnot cycle. Such a proposition is

a) Feasible

b) Impossible

c) Possible

d) Possible, but with lot of sophistications

Q10. A manufacturer claims to have a heat engine capable of developing 20 h.p. By receiving heat input of 400 kcal/mt and working between the temperatures limits of 227° C and 27° C. His claim is

a) Justified

b) Not possible

c) May be possible with lot of sophistications

d) Cost will be very high

Q11. In a Carnot cycle, heat is transferred at

a) Constant pressure

b) Constant volume

c) Constant temperature

d) Constant enthalpy

Q12. A diathermic wall is one which

a) Prevents thermal interaction

b) Permits thermal interaction

c) Encourages thermal interaction

d) Discourages thermal interaction

Q13. An adiabatic wall is one which

a) Prevents thermal interaction

b) Permits thermal interaction

c) Encourages thermal interaction

d) Discourages thermal interaction

Q14. The door of a running refrigerator inside a room was left open. Which of the following statements is correct?

a) The room will be cooled to the temperature inside the refrigerator.

b) The room will be cooled very slightly.

c) The room will be gradually warmed up.

d) The temperature of the air in room will remain unaffected.

Q15. Compressed air coming out from a punctured football

a) Becomes hotter

b) Becomes cooler

c) Remains at the same temperature

d) May become hotter or cooler depend-ing upon the humidity of the surroundings air

Q16. Water contained in a beaker can be made to boil by passing steam through it

a) At atmospheric pressure

b) At a pressure below the atmospheric pressure

c) At a pressure greater than atmospheric pressure

d) Any pressure

Q17. During throttling process

a) Heat exchange does not take place

b) No work is done by expanding steam

c) There is no change of internal energy of steam

d) All of the above

Q18. The energy of molecular motion appears as

a) Heat

b) Potential energy

c) Surface tension

d) Friction

Q19. A sudden fall in the barometer reading is asign of approaching

a) Fine weather

b) Rains

c) Storm

d) Cold wave

Q20. The unit of universal gas constant is

a) Watts/°K

b) Dynes/°C

c) Ergscm/°K

d) Erg/°K

Part 10: Objective questions and answers of Thermal Engineering