Class 11 Physics Chapter 12 Thermodynamics Solved Questions and Answers

1 Which of the following process is used to do maximum work done on the ideal gas if the gas is compressed to half of its initial volume?

A Isothermal

B Isochoric

C Isobaric

D Adiabatic

View Answer

Answer:Adiabatic

2

Let Q1, Q2 , Q2 heat given to the system in processes A, B, C respectively consider two statements

A. Q1 > Q2 > Q3

B. WA > WB > WC

A Both A & B are Correct

B Both A & B are wrong

C A is Correct Only

D B is Correct Only.

View Answer

Answer:Both A & B are Correct

3 What is the molar specific heat of a isothermal & adiabatic process respectively

A ∞ , 0

B 0, ∞

C 0, 0

D none of these

View Answer

Answer:∞ , 0

4 A vessel contains 4 mole of O₂(relative molar mass 32) at temperature T. The pressure is P. An identical vessel contains 1 mole of nitrogen of temperature 2T. find the pressure the

A P/2

B 2P

C 8P

D P

View Answer

Answer:P/2

5 During an adiabatic process the square of the pressure of a gas is proportional to the fifth power of its absolute temperature. The ratio of specific heat C_p / C_v for that gas is

A 3/5

B 4/3

C 5/3

D 3/2

View Answer

Answer:5/3

6 An ideal gas who ratio of specific heat C_p / C_v = γ is Expanded according to the law P = av²when a is constant. The ratio of final volume to Initial value is n .find the ΔU.Initial volume is V₀

A aV₀³ (n³-1) / γ-1

B aV₀² (n² - 1) / γ-1

C aV₀³ (n³ + 1) /γ+1

D aV₀² (n² + 1) /γ-1

View Answer

Answer:aV₀³ (n³-1) / γ-1

7 An ideal gas is taken through a cyclic thermodynamics process through four steps.
The amount of heat involved in the steps are Q₁ = 5960 J,Q₂ = - 5600 J,Q₃= -3000 J,Q₄ = -3600 J
respectively. The corresponding quantities of Internal energy changes are ΔU₁ = 3.760 J ,ΔU₂ = - 4800 J,ΔU₃ = -1800 J,ΔU₄ = ?

find the value ΔU₄ & net work done

A 2930 J, 960 J

B 2830 J, 900 J

C 2930 J, -960 J

D -2930 J, 960 J

View Answer

Answer:2930 J, 960 J

8 Consider the following statements

(Assertion) The internal energy of an ideal gas does not change during an Isothermal process

(Reason) The decrease in the volume of the gas is compensated by a corresponding increase in pressure when its temperature is constant in accordance with Boyle law

A Both A & R are true and R is correct Explanation of A

B Both A & R are true and R is not correct Explanation of A

C A is true R is false

D A is false but R is true

View Answer

Answer:Both A & R are true and R is correct Explanation of A.

9 It is known that curves A, B, C are Isobaric, Isothermal, Adiabatic process then when one is correct

Thermodynamics

A A - Adiabatic, B - Isothermal,, C - Isobaric

B A- Isothermal,, B - Adiabatic, C - Isobaric

C A - Isobaric, B - Isothermal C - Adiabatic

D None of these

View Answer

Answer:A - Adiabatic, B - Isothermal,, C - Isobaric

10 Consider a heat engine as shown in Fig. below Q₁ and Q₂ are heat added to heat bath T₁ and heat taken from T2 in one cycle of engine. W is the mechanical work done on the engine.

If W > 0, then possibilities are:

A Q₁ > Q₂ > 0

B Q₂ > Q₁ > 0

C Q₂ < Q₁ < 0

D Q₁ < 0, Q₂ > 0

View Answer

Answer:A, C

11 Consider a cycle followed by an engine (Fig. in below)

1 to 2 is isothermal

2 to 3 is adiabatic

3 to 1 is adiabatic

Thermodynamics

Such a process does not exist because

A heat is completely converted to mechanical energy in such a process, which is not possible.

B mechanical energy is completely converted to heat in this process,which is not possible.

C curves representing two adiabatic processes don’t intersect.

D curves representing an adiabatic process and an isothermal process don’t intersect.

View Answer

Answer:A, C

12 An ideal gas undergoes isothermal process from some initial state i to final state f. Choose the correct alternatives.

A dU = 0

B dQ= 0

C dQ = dU

D dQ = dW

View Answer

Answer:A, D

13 Which of the processes described below are irreversible?

A The increase in temperature of an iron rod by hammering it.

B A gas in a small container at a temperature T₁ is brought in contact with a big reservoir at a higher temperature T₂ which increases the temperature of the gas.

C A quasi-static isothermal expansion of an ideal gas in cylinder fitted with a frictionless piston.

D An ideal gas is enclosed in a piston cylinder arrangement with adiabatic walls. A weight W is added to the piston, resulting in compression of gas.

View Answer

Answer:A, B, C

14 If an average person jogs, hse produces 14.5 × 10³ cal/min. This is removed by the evaporation of sweat. The amount of sweat evaporated per minute (assuming 1 kg requires 580 × 10³ cal for evaporation) is

A 0.25 kg

B 2.25 kg

C 0.05 kg

D 0.20 kg

View Answer

Answer:0.25 kg

15 An ideal gas undergoes four different processes from the same initial state (Fig. in below). Four processes are adiabatic, isothermal, isobaric and isochoric. Out of 1, 2, 3 and 4 which one is adiabatic.

Thermodynamics

A 4

B 3

C 2

D 1

View Answer

Answer:2

16 Which of the following is the largest unit of energy

A Electron volt

B Joule

C Calorie

D Erg

View Answer

Answer:Calorie

17 For all the reactions what is the nature of the chemical dissociation?

A Exothermic

B Reversible

C Endothermic

D Reversible and endothermic

View Answer

Answer:Reversible and endothermic

18 Select the factor that affects the heat of reaction which is based on Kirchoff’s equation

A Molecularity

B Temperature

C Pressure

D Volume

View Answer

Answer:Temperature

19 A gas is compressed to half of its initial volume isothermally. The same gas is compressed again until the volume reduces to half through an adiabatic process. Then

A Work done during isothermal compression is more

B Work done is independent of the processes used for compression

C Work done is more during the adiabatic process

D Work done is dependent on the atomicity of the gas

View Answer