The Ideal Gas Law AP Physics 2 MCQ – Exam Style Questions etc.
The Ideal Gas Law AP Physics 2 MCQ
Unit 9: Thermodynamics
Weightage : 15–18%
Exam Style Practice Questions, The Ideal Gas Law AP Physics 2 MCQ
Question
A gas is not able to do work under which of the following circumstances?
(A) Isobaric because pressure is required for work to be done
(B) Isobaric because constant force will produce no work
(C) Isochoric because constant shape implies no changes in energy
(D) Isochoric because no change in volume implies no displacement
Answer/Explanation
Ans:(D)
Work requires displacement along with the force provided by the pressure of the gas. Therefore isochoric processes (no volume changes) involve no work.
Question
I 
II 
III 
IV 
Which graph best represents the relationship between pressure and volume for an ideal confined gas at constant temperature?
(A) I
(B) II
(C) III
(D) IV
Answer/Explanation
Ans:( C)
Since PV = nRT = constant, P and V must have an inverse relationship
Question
I
II
III
IV
Which graph best represents the relationship between the average kinetic energy of the molecules in an ideal gas and its absolute temperature?
(A) I
(B) II
(C) III
(D) IV
Answer/Explanation
Ans:(A)
Temperature is proportional to kinetic energy.
Question
Which of the following statements about the adiabatic expansion of an ideal gas is correct?
(A) The temperature may change during the expansion.
(B) The process must be isothermal.
(C) No change will occur in the internal energy.
(D) The gas cannot do any work during the expansion.
Answer/Explanation
Ans:(A)
Adiabatic means no heat transfer. However, work may change the internal energy that, in turn, may change the temperature.
Question
A student has a sample of gas with a known temperature and volume in an insulated cylinder with a piston and wants to investigate the relationship between temperature and volume. The student quickly pushes on the piston to reduce the volume a small amount and measures the new temperature and volume of the gas. This procedure is repeated to get measurements for increasingly smaller volumes of the gas. The data show that as the volume of the gas decreases, its temperature increases, which appears to contradict the ideal gas law. Which of the following modifications to the experiment would demonstrate the relationship between temperature and volume in the ideal gas law?
A Repeat the experiment with a number of different gases.
B Repeat the experiment, but compress the gas more quickly.
C Perform a new experiment in which the piston is fixed and energy is added to the gas by heating.
D Perform a new experiment with hot gas that uses an object on top of the piston to keep the pressure of the gas constant while the gas is allowed to cool.
▶️Answer/Explanation
Ans:D
The flaw in the investigation was that the pressure was not held constant. This new procedure will allow the student to determine the relationship between volume and temperature.