# Thermodynamics and Statistical Physics [GATE (Graduate Aptitude Test in Engineering) Physics]: Questions 18 - 22 of 82

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## Question 18

Appeared in Year: *2012*

### Question

MCQ▾At a certain temperature T, the average speed of nitrogen molecules in air is found to be . The most probable and the root mean square speeds of the molecules are, respectively –

### Choices

Choice (4) | Response | |
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a. | ||

b. | ||

c. | ||

d. |

## Question 19

Appeared in Year: *2012*

### Question

MCQ▾The total energy, of an ideal non – relativistic Fermi gas in three in three dimensions is given by ; where, is the number of particles and V is the volume of the gas. Identify the correct equation of state (P being the pressure) –

### Choices

Choice (4) | Response | |
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a. | ||

b. | ||

c. | ||

d. |

## Question 20

Appeared in Year: *2012*

### Question

MCQ▾Which one of the following cannot be explained by considering a harmonic approximation for the lattice vibrations in solids?

### Choices

Choice (4) | Response | |
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a. | Thermal expansion | |

b. | Dulong – Petit law | |

c. | Debye՚s law | |

d. | Optical branches in lattices |

## Question 21

Appeared in Year: *2012*

### Question

MCQ▾The isothermal compressibility, of an ideal gas at temperature and volume is given by,

### Choices

Choice (4) | Response | |
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a. | ||

b. | ||

c. | ||

d. |

## Question 22

Appeared in Year: *2012*

### Question

MCQ▾A classical gas of molecules, each of mass , is in thermal equilibrium at the absolute temperature, . The velocity component of the molecules along the Cartesian axes are and . The mean value of is –

### Choices

Choice (4) | Response | |
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a. | ||

b. | ||

c. | ||

d. |