Thermodynamics, the study of energy and its transformations, is a cornerstone of science that plays a pivotal role in various fields, including chemistry, physics, and engineering. For aspiring educators taking the Haryana Teacher Eligibility Test (HTET) 2023, a solid understanding of thermodynamics is crucial. To help you conquer this vital subject, we've crafted a detailed Multiple-Choice Questions (MCQ) guide that will not only test your knowledge but also enhance your comprehension of thermodynamics. Whether you're a student preparing for the HTET exam or simply curious about the fascinating world of energy and heat, this guide is designed to be your companion on your learning journey.
1.
Which
of the following statements is consistent with the first law of thermodynamics?
a) Energy
cannot be created or destroyed, only transformed.
b) Energy
tends to flow from colder objects to hotter objects.
c) The
entropy of a closed system always decreases.
d) Work
done by a system is always equal to the heat added to the system.
2.
What
is the name of the law that states that the total energy of an isolated system
is constant?
a) Boyle's
Law
b) Charles's
Law
c) The
First Law of Thermodynamics
d) The
Second Law of Thermodynamics
3.
When
heat is added to a gas, and the gas expands and does work on its surroundings,
what type of thermodynamic process is occurring?
a) Isothermal
b) Adiabatic
c) Isobaric
d) Isochoric
4.
Which
of the following is a measure of disorder or randomness in a thermodynamic
system?
a) Enthalpy
b) Entropy
c) Temperature
d) Pressure
5.
According
to the second law of thermodynamics, in any energy transfer or transformation,
the total entropy of an isolated system:
a) Remains
constant
b) Decreases
c) Increases
d) Becomes
negative
6.
Which
of the following statements is true regarding the efficiency of a heat engine?
a) Efficiency
is the ratio of work done to the heat added to the engine.
b) Efficiency
can be greater than 100% for ideal engines.
c) Efficiency
depends only on the temperature of the heat source.
d) Efficiency
is always 0% for real engines.
7.
What
is the name of the law that states that as the temperature of a gas decreases,
its volume also decreases if the pressure remains constant?
a) Boyle's
Law
b) Charles's
Law
c) Gay-Lussac's
Law
d) Avogadro's
Law
8.
The
temperature scale that has absolute zero as its lowest point and is commonly
used in thermodynamics is:
a) Celsius
b) Fahrenheit
c) Kelvin
d) Rankine
9.
According
to the third law of thermodynamics, what happens to the entropy of a perfect
crystal at absolute zero temperature?
a) The
entropy becomes zero.
b) The
entropy remains constant.
c) The
entropy becomes infinite.
d) The
entropy depends on the type of crystal.
10. In a heat exchanger, what is the
primary purpose of transferring heat from one fluid to another?
a) To
decrease the temperature of the fluids involved
b) To
increase the pressure of the fluids involved
c) To
increase the entropy of the fluids involved
d) To
conserve energy and improve efficiency
a) Two objects in thermal equilibrium have different temperatures.
b) Heat flows spontaneously from a colder object to a hotter object in thermal equilibrium.
c) Objects in thermal equilibrium do not exchange heat.
d) The temperature of two objects in thermal equilibrium is the same.
12. What is the name of the process in which a gas changes from a gaseous state to a liquid state by losing energy?
a) Evaporation
b) Sublimation
c) Condensation
d) Vaporization
13. Which law of thermodynamics is related to the statement "It is impossible to create a perpetual motion machine"?
a) The first law of thermodynamics
b) The second law of thermodynamics
c) The third law of thermodynamics
d) The zeroth law of thermodynamics
14. When heat is added to a system, and the system does work on its surroundings, what is the sign of the work done?
a) Positive
b) Negative
c) Zero
d) It depends on the specific conditions.
15. What is the term for the point at which a substance changes from a liquid to a gas at a constant temperature and pressure?
a) Melting point
b) Boiling point
c) Freezing point
d) Critical point
16. Which thermodynamic process involves the transfer of heat without any change in temperature?
a) Isentropic
b) Adiabatic
c) Isothermal
d) Isobaric
17. According to the ideal gas law, if the volume of a gas is held constant and its temperature is increased, what happens to its pressure?
a) Pressure decreases
b) Pressure remains constant
c) Pressure increases
d) Pressure becomes zero
18. The total energy of a closed system, which includes both internal energy and energy associated with work done, is known as:
a) Enthalpy
b) Entropy
c) Potential energy
d) Kinetic energy
19. Which law of thermodynamics states that the entropy of a perfect crystal at absolute zero temperature is zero?
a) The zeroth law of thermodynamics
b) The first law of thermodynamics
c) The second law of thermodynamics
d) The third law of thermodynamics
20. In a heat engine, what is the primary purpose of the heat input (Qh)?
a) To increase the temperature of the working substance
b) To perform mechanical work
c) To decrease the entropy of the system
d) To remove heat from the system
21. Which of the following statements is true regarding an adiabatic process?
a) Heat is transferred into or out of the system.
b) The process occurs at constant pressure.
c) There is no exchange of heat with the surroundings.
d) The system remains at a constant temperature.
22. Which thermodynamic process involves both the transfer of heat and the performance of work such that there is no change in the internal energy of the system?
a) Adiabatic
b) Isobaric
c) Isothermal
d) Isovolumetric
23. What is the primary purpose of a heat pump?
a) To remove heat from a system
b) To convert heat into mechanical work
c) To transfer heat from a colder reservoir to a hotter reservoir
d) To decrease the entropy of a system
24. What is the specific heat capacity of a substance?
a) The amount of heat required to raise the temperature of one kilogram of the substance by one degree Celsius
b) The total heat energy contained in the substance
c) The heat required to change the phase of the substance from solid to liquid
d) The heat required to change the phase of the substance from liquid to gas
25. The efficiency of a Carnot heat engine operating between two temperature reservoirs depends only on:
a) The nature of the working substance
b) The size of the engine
c) The temperature of the hot and cold reservoirs
d) The pressure of the working substance
26. Which of the following is a measure of the disorder or randomness of particles in a system?
a) Temperature
b) Pressure
c) Enthalpy
d) Entropy
27. According to the ideal gas law, what happens to the pressure of a gas if its volume is decreased while keeping the temperature constant?
a) Pressure decreases
b) Pressure remains constant
c) Pressure increases
d) Pressure becomes zero
28. What is the primary function of a heat exchanger in a thermodynamic system?
a) To convert heat into mechanical work
b) To increase the entropy of the system
c) To exchange heat between two fluids without mixing them
d) To convert thermal energy into electrical energy
29. The Kelvin-Planck statement of the second law of thermodynamics relates to:
a) Conservation of energy
b) Entropy production
c) Reversibility of processes
d) Heat transfer in adiabatic processes
30. Which of the following processes is known for maintaining a constant volume during energy exchange?
a) Isentropic
b) Adiabatic
c) Isothermal
d) Isovolumetric
31. What is the term for the maximum amount of useful work that can be obtained from a system as it approaches thermal equilibrium with its surroundings?
a) Heat capacity
b) Internal energy
c) Entropy
d) Available (or free) energy
32. Which thermodynamic process occurs at a constant volume, and there is no exchange of heat with the surroundings?
a) Adiabatic
b) Isothermal
c) Isentropic
d) Isovolumetric
33. According to the first law of thermodynamics, the change in the internal energy of a system is equal to:
a) The heat added to the system minus the work done by the system.
b) The heat added to the system plus the work done by the system.
c) The heat added to the system times the work done by the system.
d) The heat added to the system divided by the work done by the system.
34. In a thermodynamic cycle, if the net work done by the system is equal to zero, what can you conclude about the cycle?
a) The cycle is impossible.
b) The cycle is efficient.
c) The cycle is reversible.
d) The cycle is a perpetual motion machine of the first kind.
35. The efficiency of a heat engine is defined as:
a) The work done by the engine divided by the heat added to the engine.
b) The heat added to the engine divided by the work done by the engine.
c) The temperature of the hot reservoir divided by the temperature of the cold reservoir.
d) The entropy change of the engine divided by the heat added to the engine.
36. Which law of thermodynamics is associated with the statement "Energy cannot be created or destroyed, only transformed"?
a) The zeroth law of thermodynamics
b) The first law of thermodynamics
c) The second law of thermodynamics
d) The third law of thermodynamics
37. What is the name of the process in which a solid changes directly into a gas without passing through the liquid phase?
a) Evaporation
b) Sublimation
c) Condensation
d) Vaporization
38. The Clausius statement of the second law of thermodynamics relates to:
a) Conservation of energy
b) Entropy change in cyclic processes
c) Reversible processes
d) Heat transfer in adiabatic processes
39. Which of the following statements is true regarding the efficiency of a Carnot engine operating between two temperature reservoirs?
a) It is always 100%.
b) It is always less than 100%.
c) It depends on the nature of the working substance.
d) It depends on the size of the engine.
40. What is the term for the maximum theoretical efficiency of a heat engine operating between two temperature reservoirs?
a) Carnot efficiency
b) Entropy efficiency
c) Adiabatic efficiency
d) Isothermal efficiency
41. Which of the following processes is characterized by constant pressure and no change in internal energy?
a) Adiabatic
b) Isothermal
c) Isobaric
d) Isochoric
42. In a reversible thermodynamic process, what is the relationship between the change in entropy (ΔS) and the heat transfer (Q) to the system?
a) ΔS > Q
b) ΔS < Q
c) ΔS = Q
d) ΔS = 0
43. What is the term for the maximum amount of work that can be obtained from a reversible process?
a) Internal energy
b) Enthalpy
c) Helmholtz free energy
d) Gibbs free energy
44. Which of the following statements is true about the efficiency of a Carnot engine?
a) The efficiency is independent of the temperatures of the reservoirs.
b) The efficiency is always greater than 1.
c) The efficiency is maximum when the temperatures of the hot and cold reservoirs are equal.
d) The efficiency is zero.
45. What is the name of the law that states that the entropy of an isolated system tends to increase over time?
a) Boyle's Law
b) Charles's Law
c) The First Law of Thermodynamics
d) The Second Law of Thermodynamics
46. When a gas undergoes an isothermal expansion, what happens to its temperature?
a) It increases
b) It decreases
c) It remains constant
d) It depends on the initial conditions
47. Which of the following is a measure of the disorder or randomness of a system?
a) Temperature
b) Enthalpy
c) Entropy
d) Pressure
48. The heat engine with the highest possible efficiency is known as:
a) Carnot engine
b) Rankine engine
c) Diesel engine
d) Otto engine
49. Which law of thermodynamics is associated with the statement "The entropy of a perfect crystal at absolute zero is zero"?
a) The zeroth law of thermodynamics
b) The first law of thermodynamics
c) The second law of thermodynamics
d) The third law of thermodynamics
50. In which thermodynamic process does a system exchange neither heat nor work with its surroundings?
a) Adiabatic
b) Isothermal
c) Isobaric
d) Adiabatic expansion
51. Which of the following processes involves both heat transfer and work done by the system, resulting in a change in internal energy?
a) Adiabatic process
b) Isochoric process
c) Isentropic process
d) Adiabatic expansion
52. What is the name of the state of a system where it has reached its lowest possible temperature and entropy?
a) Absolute zero
b) Triple point
c) Critical point
d) Equilibrium state
53. Which law of thermodynamics is associated with the statement "Heat flows naturally from hotter objects to colder objects"?
a) The zeroth law of thermodynamics
b) The first law of thermodynamics
c) The second law of thermodynamics
d) The third law of thermodynamics
54. What is the term for the maximum amount of mechanical work that can be extracted from a closed system as it reaches equilibrium with its surroundings?
a) Enthalpy
b) Gibbs free energy
c) Helmholtz free energy
d) Internal energy
55. When a gas undergoes an isobaric process, what is kept constant?
a) Pressure
b) Volume
c) Temperature
d) Internal energy
56. In the Rankine cycle, what is the working fluid typically used in most steam power plants?
a) Oxygen
b) Nitrogen
c) Water
d) Carbon dioxide
57. What is the primary purpose of a thermal insulation material in a thermodynamic system?
a) To conduct heat efficiently
b) To absorb heat
c) To minimize heat transfer
d) To maximize entropy change
58. The entropy of a closed system tends to increase over time according to which law of thermodynamics?
a) The zeroth law of thermodynamics
b) The first law of thermodynamics
c) The second law of thermodynamics
d) The third law of thermodynamics
59. In which thermodynamic process is the volume of a gas held constant?
a) Adiabatic
b) Isothermal
c) Isobaric
d) Isochoric
60. What is the name of the thermodynamic process where a substance changes from a solid directly into a gas without becoming a liquid?
a) Sublimation
b) Evaporation
c) Condensation
d) Fusion
As you reach the end of this MCQ guide focused on
thermodynamics, you've embarked on a journey to unlock the secrets of energy,
heat, and work. Whether you're gearing up for the HTET 2023 exam or simply
expanding your knowledge, mastering thermodynamics is a significant
achievement. We hope these MCQs and explanations have provided you with the
tools you need to succeed. Remember that the world of science is rich and
ever-evolving, and your quest for knowledge is an ongoing adventure. Keep
exploring, keep learning, and may your pursuit of excellence continue to
flourish. Best of luck with your studies and your HTET 2023 endeavors!
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