Statistical Mechanics MCQs

1. What is the primary goal of statistical mechanics?

a) To study the behavior of individual particles
b) To predict macroscopic properties from microscopic interactions
c) To solve differential equations
d) To design experimental setups

Answer: b) To predict macroscopic properties from microscopic interactions

2. Which quantity represents the number of microstates corresponding to a given macrostate?

a) Partition function
b) Boltzmann factor
c) Entropy
d) Density of states

Answer: d) Density of states

3. In the canonical ensemble, which function provides the probability of a system being in a particular state?

a) Partition function
b) Free energy
c) Boltzmann factor
d) Partition coefficient

Answer: c) Boltzmann factor

4. Which statistical distribution describes the number of particles in various energy states in a system of non-interacting, indistinguishable particles?

a) Maxwell-Boltzmann distribution
b) Fermi-Dirac distribution
c) Bose-Einstein distribution
d) Poisson distribution

Answer: a) Maxwell-Boltzmann distribution

5. What is the key characteristic of a system described by the Fermi-Dirac distribution?

a) Particles are indistinguishable and follow classical statistics
b) Particles are distinguishable and follow quantum statistics
c) Particles obey the Pauli exclusion principle
d) Particles can occupy the same energy state without restriction

Answer: c) Particles obey the Pauli exclusion principle

6. In the grand canonical ensemble, which quantity is fixed?

a) Volume
b) Temperature
c) Chemical potential
d) Energy

Answer: c) Chemical potential

7. Which quantity measures the disorder or randomness in a system?

a) Enthalpy
b) Entropy
c) Free energy
d) Helmholtz free energy

Answer: b) Entropy

8. What does the Gibbs free energy
𝐺
G measure?

a) The total energy of the system
b) The maximum reversible work done by the system
c) The entropy change of the system
d) The chemical potential

Answer: b) The maximum reversible work done by the system

9. In the microcanonical ensemble, which quantities are fixed?

a) Temperature and volume
b) Energy and volume
c) Energy and number of particles
d) Temperature and chemical potential

Answer: c) Energy and number of particles

10. Which distribution describes particles in a system where indistinguishable particles follow quantum statistics and do not obey the Pauli exclusion principle?

a) Bose-Einstein distribution
b) Fermi-Dirac distribution
c) Maxwell-Boltzmann distribution
d) Poisson distribution

Answer: a) Bose-Einstein distribution

11. The concept of microstates and macrostates is fundamental to which theory?

a) Thermodynamics
b) Quantum mechanics
c) Statistical mechanics
d) Classical mechanics

Answer: c) Statistical mechanics

12. In the grand canonical ensemble, what is the role of the chemical potential
𝜇
μ?

a) It fixes the energy of the system
b) It fixes the temperature of the system
c) It fixes the number of particles in the system
d) It fixes the average number of particles in the system

Answer: d) It fixes the average number of particles in the system

13. Which ensemble is used to describe systems with fixed temperature and volume but varying number of particles?

a) Microcanonical ensemble
b) Canonical ensemble
c) Grand canonical ensemble
d) Isothermal ensemble

Answer: c) Grand canonical ensemble

14. In statistical mechanics, the concept of equipartition of energy states that:

a) All energy levels are equally occupied
b) Each degree of freedom contributes equally to the total energy
c) Energy is equally distributed among all particles
d) Energy levels are quantized and discrete

Answer: b) Each degree of freedom contributes equally to the total energy

15. The Boltzmann constant
𝑘
k is used to relate which two quantities?

a) Energy and temperature
b) Pressure and volume
c) Entropy and volume
d) Free energy and number of particles

Answer: a) Energy and temperature

16. Which distribution describes the probability of occupancy of energy states by fermions?

a) Bose-Einstein distribution
b) Maxwell-Boltzmann distribution
c) Fermi-Dirac distribution
d) Poisson distribution

Answer: c) Fermi-Dirac distribution

17. In statistical mechanics, the partition function
𝑍
Z is a function of:

a) Temperature only
b) Volume only
c) Energy levels and temperature
d) Chemical potential only

Answer: c) Energy levels and temperature

18. In the canonical ensemble, which quantity is minimized to find the equilibrium state?

a) Energy
b) Helmholtz free energy
c) Gibbs free energy
d) Entropy

Answer: b) Helmholtz free energy

19. In the microcanonical ensemble, what quantity is not fixed?

a) Energy
b) Number of particles
c) Volume
d) Temperature

Answer: d) Temperature

20. What does the Helmholtz free energy
𝐹
F represent in thermodynamics?

a) The energy available for work
b) The total internal energy
c) The work done at constant pressure
d) The maximum work obtainable at constant volume

Answer: d) The maximum work obtainable at constant volume

21. Which principle states that the entropy of a system increases with the number of accessible microstates?

a) Second Law of Thermodynamics
b) Third Law of Thermodynamics
c) Boltzmann Principle
d) Maxwell’s Demon

Answer: c) Boltzmann Principle

22. In the Bose-Einstein distribution, what characterizes the particles involved?

a) Fermions with indistinguishable states
b) Bosons with indistinguishable states
c) Classical particles with distinguishable states
d) Ideal gas particles

Answer: b) Bosons with indistinguishable states

23. Which quantity is minimized in the grand canonical ensemble to find the equilibrium state?

a) Helmholtz free energy
b) Gibbs free energy
c) Grand potential
d) Entropy

Answer: c) Grand potential