Q&A Hero

Q: When work Wis done on an ideal gas of diatomic molecules in thermal isolation the increase in the total rotational energy of the molecules is: A) 0 B) W/3 C) 2W/3 D) 2W/5 E) W

Q: When work Wis done on an ideal gas of Ndiatomic molecules in thermal isolation the temperature increases by: A) W/2Nk B) W/3Nk C) 2W/3Nk D) 2W/5Nk E) W/Nk

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

Q: An ideal gas of Nmonatomic molecules is in thermal equilibrium with an ideal gas of the same number of diatomic molecules and equilibrium is maintained as temperature is increased. The ratio of the changes in the internal energies Edia / Emonis:A) 1/2B) 3/5C) 1D) 5/3E) 2

Q: An ideal diatomic gas has a molar specific heat at constant pressure, Cp, of: A) R B) 3R/2 C) 5R/2 D) 7R/2 E) 9R/2

Q: A diatomic gas can have internal energy consisting of: 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

Q: A monatomic gas can have internal energy consisting of: 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

Q: An ideal gas of Ndiatomic molecules has temperature T.If the number of molecules is doubled without changing the temperature, the internal energy increases by: A) 0 B) NkT C) NkT D) NkT E) 3NkT

Q: The specific heat of a polyatomic gas is greater than the specific heat of a monatomic gas because: A) the polyatomic gas does more positive work when energy is absorbed as heat B) the monatomic gas does more positive work when energy is absorbed as heat C) the energy absorbed by the polyatomic gas is split among more degrees of freedom D) the pressure is greater in the diatomic gas E) a monatomic gas cannot hold as much heat

Q: The "Principle of equipartition of energy" states that the internal energy of a gas is shared equally: A) among the molecules B) between kinetic and potential energy C) among the relevant degrees of freedom D) between translational and vibrational kinetic energy E) between temperature and pressure

Q: The number of degrees of freedom of a triatomic molecule is: A) 1 B) 3 C) 6 D) 8 E) 9

Q: The number of degrees of freedom of a rigid diatomic molecule is: A) 2 B) 3 C) 4 D) 5 E) 6

Q: Assume that helium behaves as an ideal monatomic gas. If 2 moles of helium undergo a temperature increase of 100 K at constant volume, how much work is done by the gas? A) 0 J B) 1700 J C) 2500 J D) 4200 J E) 5000 J

Q: Assume that helium behaves as an ideal monatomic gas. If 2 moles of helium undergo a temperature increase of 100 K at constant pressure, how much work is done by the gas? A) 0 J B) 1700 J C) 2500 J D) 4200 J E) 5000 J

Q: Assume that helium behaves as an ideal monatomic gas. If 2 moles of helium undergo a temperature increase of 100 K at constant pressure, how much energy has been transferred to the helium as heat? A) 1700 J B) 2500 J C) 4200 J D) 5000 J E) 6700 J

Q: For a given change in temperature, the change in the internal energy of an ideal gas: A) also depends on the change in pressure B) also depends on the change in volume C) depends on whether the process is adiabatic or not D) depends on whether the process occurs at constant pressure or not E) can be calculated assuming the volume is constant

Q: Energy transferred into an ideal gas as heat: A) goes entirely into the internal energy of the gas B) goes entirely into doing work to expand the gas C) goes entirely into the internal energy of the gas only if the pressure is constant D) goes entirely into the internal energy of the gas only if the temperature is constant E) goes entirely into the internal energy of the gas only if the volume is constant

Q: The ratio of the specific heat of a gas at constant volume to its specific heat at constant pressure is: A) 1 B) less than 1 C) more than 1 D) has units of pressure/volume E) has units of volume/pressure

Q: The difference between the molar specific heat at constant pressure and the molar specific heat at constant volume for an ideal gas is: A) the Boltzmann constant k B) the universal gas constant R C) the Avogadro number NA D) kT E) RT

Q: The heat capacity at constant volume and the heat capacity at constant pressure have different values because: A) heat increases the internal energy at constant volume but not at constant pressure B) heat increases the internal energy at constant pressure but not at constant volume C) the system does work at constant volume but not at constant pressure D) the system does work at constant pressure but not at constant volume E) the system does more work at constant volume than at constant pressure

Q: An ideal gas has molar specific heat Cpat constant pressure. When the temperature of nmoles is increased by T the increase in the internal energy is: A) nCpT B) n(Cp+ R)T C) n(Cp" R)T D) n(2Cp+ R)T E) n(2Cp" R)T

Q: Consider the ratios of the heat capacities = Cp/Cvfor the three types of ideal gases: monatomic, diatomic, and polyatomic. A) is the greatest for monatomic gases B) is the greatest for polyatomic gases C) is the same only for diatomic and polyatomic gases D) is the same only for monatomic and diatomic gases E) is the same for all three

Q: The specific heat at constant volume of an ideal gas depends on: A) the temperature B) the pressure C) the volume D) the number of molecules E) none of the above

Q: The ratio of the specific heat of an ideal gas at constant volume to its specific heat at constant pressure is: A) R B) 1/R C) dependent on the temperature D) dependent on the pressure E) different for monatomic, diatomic, and polyatomic gases

Q: The specific heat Cvat constant volume of a monatomic gas at low pressure is proportional to Tnwhere the exponent nis:A) -1B) 0C) 1/2D) 1E) 2

Q: The pressure of an ideal gas of diatomic molecules is doubled by halving the volume. The ratio of the new internal energy to the old, both measured relative to the internal energy at 0 K, is: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: Both the pressure and volume of an ideal gas of diatomic molecules are doubled. The ratio of the new internal energy to the old both measured relative to the internal energy at 0 K is: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: Two ideal gases, each consisting of Nmonatomic molecules, are in thermal equilibrium with each other and equilibrium is maintained as the temperature is increased. A molecule of the first gas has mass mand a molecule of the second has mass 4m. The ratio of the internal energies E4m/Emis: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: The diagram shows three isotherms for an ideal gas, with T3-T2 the same as T2-T1. It also shows five thermodynamic processes carried out on the gas. Rank the processes in order of the change in the internal energy of the gas, least to greatest. A) I, II, III, IV, V B) V; then I, III and IV tied; then II C) V; I; then III, and IV tied; then II D) II; then I, III and IV tied; then V E) II; I; then III, IV, and V tied

Q: Ideal monatomic gas A is composed of molecules with mass mwhile 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/TBis: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: Two monatomic ideal gases are in thermal equilibrium with each other. Gas A is composed of molecules with mass mwhile gas B is composed of molecules with mass 4m. The ratio of the average molecular kinetic energy KA/KBis: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: The internal energy of an ideal gas depends on: A) the temperature only B) the pressure only C) the volume only D) the temperature and pressure only E) temperature, pressure, and volume

Q: The heat capacity at constant volume of an ideal gas depends on: A) the temperature B) the pressure C) the volume D) the number of molecules E) none of the above

Q: As the volume of an ideal gas is increased at constant pressure the average molecular speed: A) increases B) decreases C) increases at high temperature, decreases at low D) decreases at high temperature, increases at low E) stays the same

Q: As the pressure in an ideal gas is increased isothermally the average molecular speed: A) increases B) decreases C) increases at high temperature, decreases at low D) decreases at high temperature, increases at low E) stays the same

Q: Ideal monatomic gas A is composed of molecules with mass mwhile ideal monatomic gas B is composed of molecules with mass 4m. The average molecular speeds are the same if the ratio of the temperatures TA/TBis: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: Two ideal monatomic gases are in thermal equilibrium with each other. Gas A is composed of molecules with mass mwhile gas B is composed of molecules with mass 4m. The ratio of the average molecular speeds vA/vBis: A) 1/4 B) 1/2 C) 1 D) 2 E) 4

Q: According to the Maxwellian speed distribution, as the temperature increases the average speed: A) increases B) decreases C) increases at high temperatures and decreases at low D) decreases at high temperatures and increases at low E) stays the same

Q: According to the Maxwellian speed distribution, as the temperature increases the most probable speed: A) increases B) decreases C) increases at high temperatures and decreases at low D) decreases at high temperatures and increases at low E) stays the same

Q: The average speed of air molecules at room temperature is about:A) 0 m/sB) 2 m/s (walking speed)C) 30 m/s (fast car)D) 500 m/s (supersonic airplane)E) 3x108m/s (speed of light)

Q: For a gas at thermal equilibrium the average speed v, the most probable speed vp, and the root-mean-square speed vrmsare in the order: A) vp<vrms<v B) vrms<vp<v C) v<vrms<vp D) vp<v<vrms E) v<vp<vrms

Q: According to the Maxwellian speed distribution, as the temperature increases the number of molecules with speeds within a small interval near the most probable speed: A) increases B) decreases C) increases at high temperatures and decreases at low D) decreases at high temperatures and increases at low E) stays the same

Q: The Maxwellian speed distribution provides a direct explanation of: A) thermal expansion B) the ideal gas law C) heat D) evaporation E) boiling

Q: Which of the following changes when the pressure of an ideal gas is changed isothermally? A) Mean free path B) Root-mean-square molecular speed C) Internal energy D) Most probable kinetic energy E) Average speed

Q: A certain ideal gas has a temperature 300 K and a pressure 5.0 x104 Pa. The molecules have a mean free path of 4.0 x10-7m. If the temperature is raised to 350 K and the pressure is reduced to 1.0 x104 Pa the mean free path is then:A) 6.9 x10-­8mB) 9.3 x 10-­8mC) 3.4x 10-­7mD) 1.7 x 10-­6mE) 2.3 x 10-­6m

Q: If the temperature Tof an ideal gas is increased at constant pressure the mean free path: 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

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

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

Q: The mean free path of air molecules at room temperature and atmospheric pressure is about:A) 10-3mB) 10-5mC) 10-7mD) 10-9mE) 10-11m

Q: The average speeds vand molecular diameters dof five ideal gases are given below. The number of molecules per unit volume is the same for all of them. For which is the collision rate the greatest? A) v= v0and d= d0 B) v= 2v0and d= d0/2 C) v= 3v0and d= d0 D) v= v0and d= 2d0 E) v= 4v0and d= d0/2

Q: The mean free path of molecules in a gas is: A) the average distance they travel before escaping B) the average distance they travel between collisions C) the greatest distance they travel between collisions D) the shortest distance they travel between collisions E) the average distance they travel before splitting apart

Q: The mean free path of a gas molecule is: A) the shortest dimension of the containing vessel B) the cube root of the volume of the containing vessel C) approximately the diameter of a molecule D) average distance between adjacent molecules E) average distance a molecule travels between intermolecular collisions

Q: Evidence that molecules of a gas are in constant motion is: A) winds exert pressure B) two gases interdiffuse quickly C) warm air rises D) energy as heat is needed to vaporize a liquid E) gases are easily compressed

Q: In a certain gas the molecules are 5.0 x10-9 m apart on average, have a mean free path of 5.0 x 10-6 m, and have an average speed of 500 m/s. The rate at which a molecule has collision with other molecules is about:A) 10-­11 s-1B) 10-8s-1C) 1 s-­1D) 108 s-1E) 1011 s-1

Q: The temperature of a gas is most closely related to: A) the kinetic energy of translation of its molecules B) its total molecular kinetic energy C) the sizes of its molecules D) the potential energy of its molecules E) the total energy of its molecules

Q: An ideal gas is at a temperature of 320 K. What is the average translational kinetic energy of one of its molecules? A) 9.2 x 10-24J B) 1.4 x 10-23J C) 2.1 x 10-23J D) cannot tell without knowing the molar mass E) cannot tell without knowing whether the gas is monatomic or diatomic

Q: A system consists of Ngas molecules, each with mass m. Their rms speed is vrms. Their total translational kinetic energy is: A) (1/2)m(Nvrms)2 B) (1/2)N(mvrms)2 C) (1/2)mv2rms D) (1/2)Nmv2rms E) N[(1/2)mvrms]2

Q: If the molecules in a tank of hydrogen have the same rms speed as the molecules in a tank of oxygen, we may be sure that: A) the pressures are the same B) the hydrogen is at the higher temperature C) the hydrogen is at the greater pressure D) the temperatures are the same E) the oxygen is at the higher temperature

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

Q: The rms speed of an oxygen molecule at 0°C is 460 m/s. If the molar mass of oxygen is 32 g and of helium is 4 g, then the rms speed of a helium molecule at 0°C is:A) 160 m/sB) 330 m/sC) 650 m/sD) 1300 m/sE) 3700 m/s

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

Q: The temperature of low pressure hydrogen is reduced from 100°C to 20°C. The rms speed of its molecules decreases by approximately:A) 89%B) 79%C) 46%D) 21%E) 11%

Q: The pressure of an ideal gas is doubled in an isothermal process. The root-mean-square speed of the molecules: A) does not change B) increases by a factor of C) decreases by a factor of D) increases by a factor of 2 E) decreases by a factor of 1/2

Q: Oxygen has a molar mass of 32 g/mol. If 12 moles of oxygen are in a 0.1-m3container with an rms speed of 480 m/s, what is the pressure of the gas? A) 2.9 x 105Pa B) 2.1 x 106Pa C) 3.4 x 107 Pa D) 2.9 x 108 Pa E) 2.1 x 109Pa

Q: The root-mean-square speed of molecules in a gas is: A) the most probable speed B) that speed such that half the molecules are moving faster than vrmsand 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

Q: In a system of N gas molecules, the individual speeds are v1, v2, ..., vN. The rms speed of these molecules is: A) B) C) D) E)

Q: Five molecules have speeds of 2.8, 3.2, 5.8, 7.3, and 7.4 m/s. Their root-mean-square speed is closest to: A) 2.5 m/s B) 5.3 m/s C) 5.7 m/s D) 28 m/s E) 32 m/s

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

Q: A gas is confined to a cylindrical container of radius 1 cm and length 1 m. The pressure exerted on an end face, compared with the pressure exerted on the long curved face, is: A) smaller because its area is smaller B) smaller because most molecules cannot traverse the length of the cylinder without undergoing collisions C) larger because the face is flat D) larger because the molecules have a greater distance in which to accelerate before they strike the face E) none of these

Q: The force on the walls of a vessel of a contained gas is due to: A) repulsive force between gas molecules B) slight loss in average speed of a gas molecule after collision with wall C) change in momentum of a gas molecule due to collision with wall D) elastic collisions between gas molecules E) inelastic collisions between gas molecules

Q: According to the kinetic theory of gases, the pressure of a gas is due to: A) change of kinetic energy of molecules as they strike the wall B) change of momentum of molecules as they strike the wall C) average kinetic energy of the molecules D) force of repulsion between the molecules E) rms speed of the molecules

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

Q: A quantity of an ideal gas is compressed to half its initial volume. The process may be adiabatic, isothermal or occurring at constant pressure. Rank those three processes in order of the work required of an external agent, least to greatest. A) adiabatic, isothermal,constant pressure B) adiabatic, constant pressure, isothermal C) isothermal, adiabatic, constant pressure D) constant pressure, adiabatic, isothermal E) constant pressure, isothermal, adiabatic

Q: A real gas is changed slowly from state 1 to state 2. During this process no work is done on or by the gas. This process must be: A) isothermal B) adiabatic C) occurring at constant volume D) occurring at constant pressure E) a closed cycle with point 1 coinciding with point 2

Q: The pressure of an ideal gas is doubled during a process in which the energy given up as heat by the gas equals the work done on the gas. As a result, the volume is: A) doubled B) halved C) unchanged D) need more information to answer E) nonsense, the process is impossible

Q: When an ideal gas undergoes a slow isothermal expansion: A) the work done by the gas is the same as the energy absorbed as heat B) the work done by the environment is the same as the energy absorbed as heat C) the increase in internal energy is the same as the heat absorbed D) the increase in internal energy is the same as the work done by the gas E) the increase in internal energy is the same as the work done by the environment

Q: The energy absorbed as heat by an ideal gas for an isothermal process equals: A) the work done by the gas B) the work done on the gas C) the change in the internal energy of the gas D) the negative of the change in internal energy of the gas E) zero since the process is isothermal

Q: A real gas undergoes a process which can be represented as a curve on a p-Vdiagram. The work done by the gas during this process is:A) pVB) p(V2- V1)C) (p2- p1)VD) ²pdVE) V dp

Q: A real gas undergoes a process which can be represented as a curve on a p-Vdiagram. This curve is an isotherm if: A) the volume of the gas does not change B) the temperature of the gas does not change C) the pressure of the gas does not change D) the gas does no work on its environment E) the gas exchanges no heat with its environment

Q: An isothermal process for an ideal gas is represented on a p-Vdiagram by: A) a horizontal line B) a vertical line C) a portion of an ellipse D) a portion of a parabola E) a hyperbola