Question

Class 11 Physics MCQ Questions of Thermodynamics with Answers?

Answer 1

Solving the class 11 Physics MCQ Questions of Thermodynamics with Answer are often of utmost help as you’ll remember all the concepts. These MCQ Questions for class 11 with answers pave for a fast revision of the Chapter thereby helping you to boost subject knowledge.

Thermodynamics, science of the connection between heat, work, temperature, and energy. In broad terms, thermodynamics deals with the transfer of energy from one place to another and from one form to a different form.

We Cover MCQ Questions from all Important topics of Class 11 Physics Thermodynamics, list of topics are given below: –

• Introduction to the concept of thermodynamics
• Thermal equilibrium
• Zeroth law of thermodynamics
• Heat, internal energy and work
• First law of thermodynamics
• Specific heat capacity
• Thermodynamic state variables and equation of state
• Thermodynamic processes
• Heat engines
• Refrigerators and heat pumps
• Second law of thermodynamics
• Reversible and irreversible processes
• Carnot engine

Let's learn the given MCQ Questions and score high in exam.

Practice MCQ Questions for class 11 Physics Chapter-Wise

1. First law of thermodynamics states that

(a) heat is a form of energy
(b) system has pressure
(c) system has temperature
(d) system can do work

2. A system X is neither in thermal equilibrium with Y nor with Z. The systems Y and Z

(a) may be in thermal equilibrium
(b) None of these
(c) cannot be in thermal equilibrium
(d) must be in thermal equilibrium

3. Which of the following is/are macroscopic variables:

(a) Volume
(b) Temperature
(c) Pressure
(d) All of the above

4. Which of the following is a state variable?

(a) Internal energy
(b) Heat
(c) Work
(d) All of these

5. The internal energy of an ideal gas depends upon

(a) temperature
(b) specific volume
(c) pressure
(d) density

6. The state of a thermodynamic system is represented by

(a) pressure, volume and temperature
(b) volume only
(c) pressure only
(d) number of moles

7. Which of the following parameters does not characterize the thermodynamic state of matter?

(a) Work
(b) Temperature
(c) Pressure
(d) Volume

8. The internal energy of a substance:

(a) decrease with increase in temperature
(b) increase with increase in temperature
(c) remains unaffected with change in temperature
(d) calculated by E = mc²

9. The variable defined by Zeroth law of thermodynamics is

(a) temperature
(b) internal energy
(c) work
(d) All of these

10. The first operation involved in a Carnot cycle is

(a) isothermal expansion
(b) adiabatic expansion
(c) isothermal compression
(d) adiabatic compression

11. “Heat cannot by itself flow from a body at lower temperature to a body at higher temperature” is a statement or consequence of

(a) second law of thermodynamics
(b) conservation of momentum
(c) conservation of mass
(d) first law of thermodynamics

12. Air conditioner is based on the principle of

(a) refrigerator
(b) first law of thermodynamics
(c) None of these
(d) Carnot cycle

13. Which of the following processes is reversible?

(a) Isothermal compression
(b) Electrical heating of a nichrome wire
(c) Transfer of heat by radiation
(d) Transfer of heat by conduction

14. Which of the following statements is incorrect?

(a) All reversible cycles have same efficiency
(b) Reversible cycle has more efficiency than an irreversible one
(c) Carnot cycle is a reversible one
(d) Carnot cycle has the maximum efficiency in all cycles

15. A refrigerator is a

(a) heat engine working in backward direction
(b) air cooler
(c) an electric motor
(d) heat engine

16. Two cylinders A and B of equal capacity are connected to each other via a stop cock. A contains an ideal gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stop cock is suddenly opened. The process is : 

(a) adiabatic
(b) isochoric
(c) isobaric
(d) isothermal

17. The efficiency of a Carnot engine depends upon:

(a) the temperature of the sink only
(b) the temperatures of the source and sink
(c) the volume of the cylinder of the engine
(d) the temperature of the source only

18. A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then -

(a) compressing the gas through adiabatic process will require more work to be done
(b) compressing the gas isothermally or adiabatically will require the  same amount work
(c) which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas
(d) compressing the gas isothermally will require more work to be done

19. If ΔU and ΔW represent the increase in internal energy and work done by the system respectively in a thermodynamical process, which of the following is true?

(a) ΔU = −ΔW,  in a adiabatic process
(b) ΔU = ΔW,  in a isothermal process
(c) ΔU = ΔW, in a adiabatic process
(d) ΔU = −ΔW,  in a isothermal process

20. In thermodynamic processes which of the following statements is not true?

(a) In an isochoric process pressure remains constant
(b) In an isothermal process the temperature remains constant
(c) In an adiabatic process the system is insulated from the surroundings
(d) In an adiabatic process PV^γ= constant

21. If Q, E and W denote respectively the heat added, change in internal energy and the work done in a closed cyclic process, then

(a) W=0
(b) Q=W=0
(c) E=0
(d) Q=0

22. A sink, that is the system where heat is rejected, is essential for the conversion of heat into work. From which law the above inference follows?

(a) zeroth
(b) First
(c) Second
(d) Third

23. Which of the following is not a thermodynamics co-ordinate?

(a) P
(b) T
(c) V
(d) R

24. In isothermal expansion the pressure is determined by :

(a) temperature only
(b) compressibility only
(c) both temperature and compressibility
(d) latent heat

25.The specific heat of a gas in an isothermal process is-

(a) Infinite
(b) Zero
(c) Negative
(d) Remains constant

Answer 2

1. Answer: (d) system can do work

Explanation: According to First law of thermodynamics,dQ = dU + dW a system can do work and increase it's internal energy provided we supply heat.

2. Answer: (a) may be in thermal equilibrium

Explanation: By zeroth law of thermodynamics, there are three parts to the system. Let's say x,y,z.It is given that in the question is, A system Y is neither in thermal equilibrium with Y nor with Z. But, their is possibility by Zeroth law of theromodynamics that Y and Z may be in thermol eqyuilibrium.

3. Answer: (d) All of the above

Explanation: Macroscopic variable is a measurable quantity used to describe the complete state of the system. The state of a macroscopic system in equilibrium can be described in terms of measurable properties as temperature, pressure, and volume, which are also known as thermodynamic variables.

4. Answer: (a) Internal energy

Explanation: State function is a proterty of a system that depends only on its present state, which is completely determined by variables such as temperature and pressure. Thus. Internal energy and volume are state function. On the other hand, heat and work are not state functions becasue they are not properties of a system

5. Answer: (a) temperature

Explanation: The internal energy and enthalpy of ideal gases depends only on temperature, not on volume or pressure.

6. Answer: (a) pressure, volume and temperature

Explanation: The state of a system is defined by ascribing values to a sufficient number of variables. In mechanics, the state of a body is specified by means of a few measurable quantities, such as the position of centre of mass, its velocity and acceleration etc. In thermodynamics, however we disregard these mechanical coordinates and instead consider the interior of the system, find out directly or indirectly by experiments same measurable quantities upon which the internal state of the system for all thermodynamic purposes, the state of a system can be represented by specifying its pressure p, volume V and the temperature T provided the system is in equilibrium.

7. Answer: (a) Work

Explanation: Work does not characterized the thermodynamic state of matter, it is a path function giving only relationship between two quantities.

8. Answer: (b) increase with increase in temperature

Explanation: The internal energy of a substance always increases with increase in temperature.

9. Answer: (a) temperature

Explanation: Zeroth law defines temperature and first law defines internal energy.

10. Answer: (a) isothermal expansion

Explanation: The Carnot cycle consists of the following four processes: A reversible isothermal gas expansion process. In this process, the ideal gas in the system absorbs qin amount heat from a heat source at a high temperature Thigh, expands and does work on surroundings.

11. Answer: (a) second law of thermodynamics

Explanation: From Kelvin Plank statement and Claussius's statement we can say that heat can not be flow form lower temperature to higher temperature until and unless we are adding any external source like heat pump, which justifies second law of thermodynamics.

12. Answer: (a) refrigerator

Explanation: An air conditioner works using a thermodynamic cycle called the refrigeration cycle. It does this by changing the pressure and state of the refrigerant to absorb or release heat. The refrigerant (aka coolant) absorbs heat from inside of your home and then pumps it outside.

13. Answer: (a) Isothermal compression

Explanation: Isothermal compression is reversible, for example, Carnot cycle, heat engine.

14. Answer: (a) All reversible cycles have same efficiency

Explanation: We know that carnot cycle is reversible cycle, and reversible cycle has maximum efficiency of all other cycles.

15. Answer: (a) heat engine working in backward direction 

Explanation: As we know, a heat engine is something that converts heat into mechanical work.
Usually, a refrigerator is a device that is used to cool things.But according to the second law of thermodynamics, a refrigerator is a device which is used to turn mechanical work into heat. Therefore, we can say that a refrigerator is a heat engine that works in a backward direction.

16. Answer: (a) adiabatic

Explanation: The entire system is completely insulated and the free expansion of the gas will take place, the temperature of the gas will remain constant. So the process will be adiabatic.

17. Answer: (b) the temperatures of the source and sink

Explanation: \(\eta=1-\frac{T_2}{T_1}\)

It depends on the temperature of source and sink.

18. Answer: (a) compressing the gas through adiabatic process will require more work to be done

Explanation: W_ext = negative of area with volume-axis

W_(adiabatic) > W_(isothermal)

19. Answer: (a) ΔU = −ΔW,  in a adiabatic process

Explanation: ΔQ = ΔU + W

For an adiabatic process, ΔQ = 0.

∴ΔU = −W

20. Answer: (a) In an isochoric process pressure remains constant

Explanation: Isochoric → Volume constant

21. Answer: (c) E=0

Explanation: Internal energy depends only on the initial and final states of temperature and not on the path. In a cyclic process, as initial and final states are the same, the internal energy change is zero. Hence E is ΔU, the internal energy change.

22. Answer: (c) Second

Explanation: A sink, that is the system where heat is rejected, is essential for the conversion of heat into work. Otherwise, change in entropy of the universe won't be positive.Which is must according to the second law of thermodynamics.

23. Answer: (d) R

Explanation: R is a constant and is not a thermodynamic constant.

24. Answer: (b) compressibility only

Explanation: In isothermal expansion, the temperature remains constant over the process.Thus, the pressure is only variable dependent on the volume or the compressibility of the system.

25. Answer: (a) Infinite

Explanation: In isothermal process temperature remains constant. i.e.

ΔT=0. Hence according to \(C=\frac{Q}{m\Delta T}\) ⇒C_iso = ∞

Click here to practice MCQ Questions for Thermodynamics class 11