Question 1

The ratio of the specific heat of an ideal gas at constant volume to its specific heat at constant pressure is:

Accepted Answer

A)  R 
B)  1/R 
C)  dependent on the temperature 
D)  dependent on the pressure 
E)  different for monatomic, diatomic, and polyatomic gases 
A)  R 
B)  1/R 
C)  dependent on the temperature 
D)  dependent on the pressure 
E)  different for monatomic, diatomic, and polyatomic gases

Question 2

Ideal monatomic gas A is composed of molecules with mass m while ideal monatomic gas B is composed of molecules with mass 4m. The average molecular energies are the same if the ratio of the temperatures TA/TB is:

Accepted Answer

A)  1/4 
B)  1/2 
C)  1 
D)  2 
E)  4 
A)  1/4 
B)  1/2 
C)  1 
D)  2 
E)  4

Question 3

A sample of argon gas (molar mass 40 g) is at four times the absolute temperature of a sample of hydrogen gas (molar mass 2 g). The ratio of the rms speed of the argon molecules to that of the hydrogen is:

Accepted Answer

A)  1 
B)  5 
C)  1/5 
D)    
E)    
A)  1 
B)  5 
C)  1/5 
D)    
E)

Question 4

The speeds of 25 molecules are distributed as follows: 5 in the range from 2 to 3 m/s, 10 in the range from 3 to 4 m/s, 5 in the range from 4 to 5 m/s, 3 in the range from 5 to 6 m/s, 1 in the range from 6 to 7 m/s, and 1 in the range from 7 to 8 m/s. Their average speed is about:

Accepted Answer

A)  2 m/s 
B)  3 m/s 
C)  4 m/s 
D)  5 m/s 
E)  6 m/s 
A)  2 m/s 
B)  3 m/s 
C)  4 m/s 
D)  5 m/s 
E)  6 m/s

Question 5

Two monatomic ideal gases are in thermal equilibrium with each other. Gas A is composed of molecules with mass m while gas B is composed of molecules with mass 4m. The ratio of the average molecular kinetic energy KA/KB is:

Accepted Answer

A)  1/4 
B)  1/2 
C)  1 
D)  2 
E)  4 
A)  1/4 
B)  1/2 
C)  1 
D)  2 
E)  4

Question 6

The specific heat Cv at constant volume of a monatomic gas at low pressure is proportional to Tn where the exponent n is:

Accepted Answer

A)  -1 
B)  0 
C)  1/2 
D)  1 
E)  2 
A)  -1 
B)  0 
C)  1/2 
D)  1 
E)  2

Question 7

The root-mean-square speed of molecules in a gas is:

Accepted Answer

A)  the most probable speed 
B)  that speed such that half the molecules are moving faster than vrms and the other half are moving slower 
C)  the average speed of the molecules 
D)  the square root of the square of the average speed 
E)  none of the above 
A)  the most probable speed 
B)  that speed such that half the molecules are moving faster than vrms and the other half are moving slower 
C)  the average speed of the molecules 
D)  the square root of the square of the average speed 
E)  none of the above

Question 8

Air is pumped into a bicycle tire at constant temperature. The pressure increases because:

Accepted Answer

A)  more molecules strike the tire wall per second 
B)  the molecules are larger 
C)  the molecules are farther apart 
D)  each molecule is moving faster 
E)  each molecule has more kinetic energy 
A)  more molecules strike the tire wall per second 
B)  the molecules are larger 
C)  the molecules are farther apart 
D)  each molecule is moving faster 
E)  each molecule has more kinetic energy

Question 9

An ideal gas occupies 12 liters at 293 K and 1 atm (76 cm Hg). Its temperature is now raised to 373 K and its pressure increased to 215 cm Hg. The new volume is:

Accepted Answer

A)  3.3 liters 
B)  5.4 liters 
C)  27 liters 
D)  46 liters 
E)  none of these 
A)  3.3 liters 
B)  5.4 liters 
C)  27 liters 
D)  46 liters 
E)  none of these

Question 10

A diatomic gas can have internal energy consisting of:

Accepted Answer

A)  translational motion only 
B)  rotational motion only 
C)  oscillatory motion only 
D)  both translational and rotational motion 
E)  translational, rotational, and oscillatory motion, depending on temperature 
A)  translational motion only 
B)  rotational motion only 
C)  oscillatory motion only 
D)  both translational and rotational motion 
E)  translational, rotational, and oscillatory motion, depending on temperature

Question 11

Three gases, one consisting of monatomic molecules, the second consisting of diatomic molecules, and the third consisting of polyatomic molecules, are in thermal equilibrium with each other and remain in thermal equilibrium as the temperature is raised. All have the same number of molecules. The gases with the least and greatest internal energy are respectively:

Accepted Answer

A)  polyatomic, monatomic 
B)  monatomic, polyatomic 
C)  diatomic, monatomic 
D)  polyatomic, diatomic 
E)  all have equal internal energy 
A)  polyatomic, monatomic 
B)  monatomic, polyatomic 
C)  diatomic, monatomic 
D)  polyatomic, diatomic 
E)  all have equal internal energy

Question 12

During a reversible adiabatic expansion of an ideal gas, which of the following is NOT true?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 13

If the temperature T of an ideal gas is increased at constant pressure the mean free path:

Accepted Answer

A)  decreases in proportion to 1/T 
B)  decreases in proportion to 1/T2 
C)  increases in proportion to T 
D)  decreases in proportion to T2 
E)  does not change 
A)  decreases in proportion to 1/T 
B)  decreases in proportion to 1/T2 
C)  increases in proportion to T 
D)  decreases in proportion to T2 
E)  does not change

Question 14

The mean free path of molecules in a gas is proportional to:

Accepted Answer

A)  the molecular cross-sectional area 
B)  the reciprocal of the molecular cross-sectional area 
C)  the root-mean-square molecular speed 
D)  the square of the average molecular speed 
E)  the molar mass 
A)  the molecular cross-sectional area 
B)  the reciprocal of the molecular cross-sectional area 
C)  the root-mean-square molecular speed 
D)  the square of the average molecular speed 
E)  the molar mass

Question 15

The ratio of the specific heat of a gas at constant volume to its specific heat at constant pressure is:

Accepted Answer

A)  1 
B)  less than 1 
C)  more than 1 
D)  has units of pressure/volume 
E)  has units of volume/pressure 
A)  1 
B)  less than 1 
C)  more than 1 
D)  has units of pressure/volume 
E)  has units of volume/pressure

Question 16

Which of the following changes when the pressure of an ideal gas is changed isothermally?

Accepted Answer

A)  Mean free path 
B)  Root-mean-square molecular speed 
C)  Internal energy 
D)  Most probable kinetic energy 
E)  Average speed 
A)  Mean free path 
B)  Root-mean-square molecular speed 
C)  Internal energy 
D)  Most probable kinetic energy 
E)  Average speed

Question 17

The mean free path of molecules in a gas is proportional to:

Accepted Answer

A)  the molecular diameter 
B)  the reciprocal of the molecular diameter 
C)  the molecular concentration 
D)  the reciprocal of the molecular concentration 
E)  the average molecular speed 
A)  the molecular diameter 
B)  the reciprocal of the molecular diameter 
C)  the molecular concentration 
D)  the reciprocal of the molecular concentration 
E)  the average molecular speed

Question 18

The temperature of n moles of an ideal monatomic gas is increased by $\Delta$T at constant volume. The energy Q absorbed as heat, change $\Delta$Eint in internal energy, and work W done by the environment are given by:

Accepted Answer

A)  Q = (5/2)nR$\Delta$T, $\Delta$Eint = 0, W = 0 
B)  Q = (3/2)nR$\Delta$T, $\Delta$Eint = (3/2)nR$\Delta$T, W = 0 
C)  Q = (3/2)nR$\Delta$T, $\Delta$Eint = (1/2)nR$\Delta$T, W = -nR$\Delta$T 
D)  Q = (5/2)nR$\Delta$T, $\Delta$Eint = (3/2)nR$\Delta$T, W = -nR$\Delta$T 
E)  Q = (3/2)nR$\Delta$T, $\Delta$Eint = 0, W = -(3/2)nR$\Delta$T 
A)  Q = (5/2)nR$\Delta$T, $\Delta$Eint = 0, W = 0 
B)  Q = (3/2)nR$\Delta$T, $\Delta$Eint = (3/2)nR$\Delta$T, W = 0 
C)  Q = (3/2)nR$\Delta$T, $\Delta$Eint = (1/2)nR$\Delta$T, W = -nR$\Delta$T 
D)  Q = (5/2)nR$\Delta$T, $\Delta$Eint = (3/2)nR$\Delta$T, W = -nR$\Delta$T 
E)  Q = (3/2)nR$\Delta$T, $\Delta$Eint = 0, W = -(3/2)nR$\Delta$T

Question 19

The mass of an oxygen molecule is 16 times that of a hydrogen molecule. At room temperature, the ratio of the rms speed of an oxygen molecule to that of a hydrogen molecule is:

Accepted Answer

A)  16 
B)  4 
C)  1 
D)  1/4 
E)  1/16 
A)  16 
B)  4 
C)  1 
D)  1/4 
E)  1/16

Question 20

An ideal gas is at a temperature of 320 K. What is the average translational kinetic energy of one of its molecules?

Accepted Answer

A)  9.2 x 10-24 J 
B)  1.4 x 10-23 J 
C)  2.1 x 10-23 J 
D)  cannot tell without knowing the molar mass 
E)  cannot tell without knowing whether the gas is monatomic or diatomic 
A)  9.2 x 10-24 J 
B)  1.4 x 10-23 J 
C)  2.1 x 10-23 J 
D)  cannot tell without knowing the molar mass 
E)  cannot tell without knowing whether the gas is monatomic or diatomic

Exam 19: The Kinetic Theory of Gases

The ratio of the specific heat of an ideal gas at constant volume to its specific heat at constant pressure is:

Ideal monatomic gas A is composed of molecules with mass m while ideal monatomic gas B is composed of molecules with mass 4m. The average molecular energies are the same if the ratio of the temperatures TA/TB is:

A sample of argon gas (molar mass 40 g) is at four times the absolute temperature of a sample of hydrogen gas (molar mass 2 g). The ratio of the rms speed of the argon molecules to that of the hydrogen is:

The speeds of 25 molecules are distributed as follows: 5 in the range from 2 to 3 m/s, 10 in the range from 3 to 4 m/s, 5 in the range from 4 to 5 m/s, 3 in the range from 5 to 6 m/s, 1 in the range from 6 to 7 m/s, and 1 in the range from 7 to 8 m/s. Their average speed is about:

Two monatomic ideal gases are in thermal equilibrium with each other. Gas A is composed of molecules with mass m while gas B is composed of molecules with mass 4m. The ratio of the average molecular kinetic energy KA/KB is:

The specific heat Cv at constant volume of a monatomic gas at low pressure is proportional to Tn where the exponent n is:

The root-mean-square speed of molecules in a gas is:

Air is pumped into a bicycle tire at constant temperature. The pressure increases because:

An ideal gas occupies 12 liters at 293 K and 1 atm (76 cm Hg). Its temperature is now raised to 373 K and its pressure increased to 215 cm Hg. The new volume is:

A diatomic gas can have internal energy consisting of:

During a reversible adiabatic expansion of an ideal gas, which of the following is NOT true?

If the temperature T of an ideal gas is increased at constant pressure the mean free path:

The mean free path of molecules in a gas is proportional to:

The ratio of the specific heat of a gas at constant volume to its specific heat at constant pressure is:

Which of the following changes when the pressure of an ideal gas is changed isothermally?

The mean free path of molecules in a gas is proportional to:

The temperature of n moles of an ideal monatomic gas is increased by Δ\DeltaΔ T at constant volume. The energy Q absorbed as heat, change Δ\DeltaΔ Eint in internal energy, and work W done by the environment are given by:

The mass of an oxygen molecule is 16 times that of a hydrogen molecule. At room temperature, the ratio of the rms speed of an oxygen molecule to that of a hydrogen molecule is:

An ideal gas is at a temperature of 320 K. What is the average translational kinetic energy of one of its molecules?

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Ideal monatomic gas A is composed of molecules with mass m while ideal monatomic gas B is composed of molecules with mass 4m. The average molecular energies are the same if the ratio of the temperatures T_A/T_B is:

Two monatomic ideal gases are in thermal equilibrium with each other. Gas A is composed of molecules with mass m while gas B is composed of molecules with mass 4m. The ratio of the average molecular kinetic energy K_A/K_B is:

The specific heat C_v at constant volume of a monatomic gas at low pressure is proportional to Tⁿ where the exponent n is:

The temperature of n moles of an ideal monatomic gas is increased by $\Delta$ T at constant volume. The energy Q absorbed as heat, change $\Delta$ E_int in internal energy, and work W done by the environment are given by: