APB – Multiple Choice Practice QuestionsHeat Kinetics and Thermodynamics

1) Which of the following could NOT be used to indicate a temperature change? A change in:A) color of a metal rodB) length of a liquid columnC) pressure of a gas at constant volumeD) electrical resistanceE) mass of one mole of gas at constant pressure

2) A mass m of helium gas is in a container of constant volume V. It is initially at pressure p and absolute (Kelvin) temperature T. Additional Helium is added, bringing the total mass of helium gas to 3m. After this addition, the temperature is found to be 2T. What is the gas pressure?A) 2/3 pB) 3/2 pC) 2 pD) 3 pE) 6 p

3) A gas can be taken from state a to state c by two different reversible processes, ac or abc. During the direct process ac, 20 J of work are done by the system and 30 J of heat are added to the system. During the process abc, 25 J of heat are added to the system. How much work is done by the system during abc?A) 5 JB) 10 JC) 15 JD) 20 JE) 25 J

4) What temperature change on the Kelvin scale is equivalent to a 10 degree change on the Celsius scaleA) 283 KB) 273 KC) 18 KD) 10 KE) 0 K

5) Which would be the most comfortable temperature for your bath water?A) 0 CB) 40 KC) 110 CD) 310 KE) 560 K

6) The theoretical (Carnot) efficiency of a heat engine operating between 600C and 100C isA) 16.7 %B) 20.0 %C) 42.7 %D) 57.3 %E) 83.3 %

7) When an ideal gas is isothermally compressedA) thermal energy flows from the gas to the atmosphereB) the temperature of the gas decreasesC) no thermal energy enters or leaves the gasD) the temperature of the gas increasesE) thermal energy flows from the surroundings to the gas

8) Which of the following is always true for an isothermal process of an ideal gas?A) The internal energy does not changeB) No heat flows into or out of the systemC) The pressure does not changeD) The volume does not changeE) No work is done by or on the system

9) The average speed of the atoms of a gas a 100 K is 200 m/s. What would most nearly be the average speed of the atoms at 300 K?A) 67 m/sB) 140 m/sC) 200 m/sD) 350 m/sE) 600 m/s

10) Which of the following temperatures would be most appropriate to keep milk at inside a refrigerator?A) -20 CB) 5 KC) 40 CD) 278 KE) 350 K

11) A heat engine takes in 200 J of thermal energy and performs 50 J of work in each cycle. What is its efficiency?A) 500 %B) 400 %C) 25 %D) 20 %E) 12 %

12) A rectangular piece of metal 3cm high by 6cm wide has a hole cut in its center 1cm high by 4cm wide as shown in the diagram at right. As the metal is warmed from 0C to 100C what will happen to the dimensions of the hole?A) both height and width will increaseB) both height and width will decreaseC) both height and width will remain unchangedD) height will decrease while width will increaseE) height will increase while width will decrease

13) A gas is enclosed in a cylindrical piston. When the gas is heated from 0C to 100C, the piston is allowed to move to maintain a constant pressure. According to the Kinetic-Molecular Theory of MatterA) the mass of the gas will increaseB) the number of molecules of gas must increaseC) the size of the individual molecules has increaseD) the average speed of the molecules has increasedE) the molecules continue to strike the sides of the container with the same energy.

14) Two containers are filled with gases at the same temperature. In the container on the left is a gas of molar mass 2M, volume 2V, and number of moles 2n. In the container on the right is a gas of molar mass M, volume V, and moles n. Which is most nearly the ratio of the pressure of the gas on the left to the pressure of the gas on the right?A) 1:1

B) 2:1C) 4:1D) 8:1E) 16:1

15) A thermally insulating container has a membrane separating the container into two equal parts. In one part is a vacuum. In the other part is an ideal gas of temperature T and internal energy U. The membrane is punctured and the gas rushes into the region which was a vacuum. After the system has returned to equilibrium, which of the following is NOT true for the gas?A) The temperature of the gas is unchangedB) No work is done by the gas on the surroundingsC) There is no heat exchanged by the gas with the surroundingsD) There is no entropy change of the systemE) The internal energy of the gas is unchanged

16) According to the kinetic theory of gases, when the absolute temperature of an ideal gas doubles, the average kinetic energy of the molecules of the gasA) quadruplesB) doublesC) stays the sameD) is cut in halfE) is quartered

17) When gas escapes from a pressurized cylinder, the stream of gas feels cool. This is because ______A) work is being done at the expense of thermal energyB) of the convection inside the cylinderC) pressurized cylinders are good thermal insulatorsD) the gas inside the cylinder is actually frozenE) the moisture in the air condenses and cools

18) A monoatomic ideal gas is used as the working substance for the Carnot cycle shown in the figure. Processes AB and CD are

isothermal, while BC and DA are adiabatic. During process AB, there are 400 J of work done by the gas on the surroundings. How much heat is expelled by the gas during process CD?A) 1600 JB) 800 JC) 400 JD) 200 JE) 100 J

19) Two identical samples of an ideal gas are in equal volume containers A and B with the same pressure and temperature. The gas in A performs work W on the surroundings during an isobaric process before the pressure is reduced isochorically to ½ its initial amount. The gas in B has its pressure reduced isochorically to ½ its initial volume and then the gas performs work W on the surroundings during an isobaric process. After the processes are performed on the gases, which is at a higher temperature?A) AB) BC) each has equal temperatureD) The value of W is necessary to answer this questionE) The value of W and both initial pressure and volume is necessary to answer this question.

20) If two molecules in a gas collide, thenA) total momentum is always exchangedB) velocities are always exchangedC) both molecules always speed upD) total kinetic energy always increasesE) velocities are always unchanged

21) The volume of an ideal gas changes as the gas undergoes an isobaric (constant pressure) process starting from temperature 273C and ending at 546C. What is the ratio of the new volume of the gas to the old volume (Vnew/Vold)

22) Container A has a sample of monatomic ideal gas, while container B has a sample of diatomic ideal gas. The two gases start with the same initial temperature, volume, pressure and number of moles of molecules. Each gas now undergoes a reversible adiabatic process that cuts the pressure in half. Which sample of gas is now at the higher temperature?A) the gas in container AB) the gas in container BC) the gases have equal temperatureD) the initial value of the pressure is necessary to answer the questionE) It is invalid to ask … it is not possible for an adiabatic process to reduce pressure.

23) The PV diagram shows four different possible reversible processes performed on a monatomic ideal gas. Process A is isobaric, B is isothermal, C is adiabatic, D is isochoric. For which process does the temperature of the gas decrease. A) AB) CC) C and DD) B,C,DE) All four processes

24) A new monatomic ideal gas is discovered. A pure 4 mole sample is sitting in a container at equilibrium in a 20 C environment. According to the kinetic theory of gases, what is the average kinetic energy per molecule for this gasA) 4.14 x 10-22 JB) 6.07 x 10-21 JC) 2.02 x 10-21 JD) 3652 JE) The molar mass of the gas is needed to answer this question

25) A uniform square piece of metal has initial sides of length Lo and a square piece is cut out of the center. The temperature of the metal is now raised so that the side lengths are increased by 4%. What has happened to the area of the square piece cut out of the center of the metal

ANSWERS - THERMO1) E2) E3) C4) D5) D6) D7) A8) A9) D10) D11) C12) A13) D14) A15) D16) B17) A18) E19) B20) A21) B22) B23) C24) B25) B