Two tanks of gas, one of hydrogen, H2, and one of helium, He, contain equal numbers of moles of gas. The gram-molecular mass of He is twice that of H2 . Both tanks of gas are at the same temperature, 293 K. Which statement(s) below is(are) correct when we ignore vibrational motion?
a. The total internal energy of the hydrogen is the same as that of the helium.
b. The total internal energy of the hydrogen is 1.4 times that of the helium.
c. The total internal energy of the helium is 1.4 times that of the hydrogen.
d. The total internal energy of the hydrogen is 1.67 times that of the helium.
e. The total internal energy of the helium is 1.67 times that of the hydrogen.
[Ques. 2] The temperature of a quantity of an ideal gas is
a. one measure of its ability to transfer thermal energy to another body.
b. proportional to the average molecular kinetic energy of the molecules.
c. proportional to the internal energy of the gas.
d. correctly described by all the statements above.
e. correctly described only by (a) and (b) above.
[Ques. 3] When we consider a thin horizontal layer of the atmosphere, of thickness dy, of area A, with pressure P on the bottom, with an average mass m per molecule, and nV molecules per unit volume, the magnitude of the difference of the pressure at the top and bottom of the layer is given by dP =
a. mgdy.
b. mgnVdy.
c. mgAdy.
d. mgnVAdy.
e. mgnVAPdy.
[Ques. 4] The internal energy of n moles of an ideal gas depends on
a. one state variable T.
b. two state variables T and V.
c. two state variables T and P.
d. three state variables T, P and V.
e. four variables R, T, P and V.
[Ques. 5] Assume molecules have an average diameter of 3.00 1010 m. How many times larger is the mean free path than the diameter at one atmosphere and 0C?
a. 500
b. 300
c. 700
d. 1 000
e. 2 500
[Ques. 6] Nitrogen gas is heated by a pulsed laser to 50 000 K. If the diameter of the nitrogen atoms is assumed to be 1.0 1010 m, and the pressure is 1.0 atm, what is the mean free path?
a. 1.5 104 m
b. 1.5 107 m
c. 1.5 1010 m
d. 1.5 1014 m
e. 1.5 102 m
[Ques. 7] Assume 3.0 moles of a diatomic gas has an internal kinetic energy of 10 kJ. Determine the temperature of the gas after it has reached equilibrium.
a. 270 K
b. 160 K
c. 800 K
d. 1 550 K
e. 400 K
[Ques. 8] When we say that the speed of sound is measured under adiabatic conditions we assume that
a. the time associated with heat conduction is slow relative to the speed of the wave.
b. no heat can flow between the system and its surroundings.
c. the speed of the wave is directly proportional to the bulk modulus.
d. the speed of the wave is proportional to the square root of the bulk modulus.
e. air is an ideal gas.
[Ques. 9] An ideal gas is allowed to expand adiabatically until its volume increases by 50. By approximately what factor is the pressure reduced? ( = 5/3.)
a. 1.5
b. 2.0
c. 2.5
d. 3.0
e. 3.5
[Ques. 10] During an adiabatic compression, a volume of air decreases to 1/4 its original size. Calculate its final pressure if its original pressure was 1 atm. (Assume the air behaves like an ideal gas with = 1.4.)
a. 7.0 atm
b. 5.6 atm
c. 3.5 atm
d. 2.2 atm
e. 0.14 atm
Quick Reply
