physics : class11 Diatomic Gas : Internal Energy : Thermodynamics MCQ Questions and Answers
Practice important
Diatomic Gas
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. For an ideal diatomic gas at ordinary temperatures, how many degrees of freedom are considered active?
A.
2
B.
3
C.
5
D.
7
Correct Answer:
5
Explanation:
A diatomic gas has 3 translational and 2 rotational degrees of freedom at ordinary temperatures, giving a total of 5 active degrees of freedom.
2. What is the internal energy of n moles of an ideal diatomic gas at temperature T, when vibrational motion is neglected?
A.
nRT
B.
3nRT/2
C.
5nRT/2
D.
7nRT/2
Correct Answer:
5nRT/2
Explanation:
For a diatomic gas with 5 active degrees of freedom, internal energy is U = (f/2)nRT = (5/2)nRT.
3. The molar internal energy of an ideal diatomic gas at ordinary temperature is:
A.
RT/2
B.
3RT/2
C.
5RT/2
D.
7RT/2
Correct Answer:
5RT/2
Explanation:
For one mole of a diatomic gas, U = (5/2)RT when vibrational degrees of freedom are neglected.
4. What is the molar specific heat at constant volume of an ideal diatomic gas at ordinary temperatures?
A.
R/2
B.
3R/2
C.
5R/2
D.
7R/2
Correct Answer:
5R/2
Explanation:
For a diatomic gas with 5 active degrees of freedom, the molar heat capacity at constant volume is Cv = (5/2)R.
5. If the temperature of one mole of an ideal diatomic gas increases by ΔT, what is the increase in its internal energy?
A.
RΔT/2
B.
3RΔT/2
C.
5RΔT/2
D.
7RΔT/2
Correct Answer:
5RΔT/2
Explanation:
The change in internal energy is ΔU = nCvΔT. For one mole of a diatomic gas, Cv = 5R/2, so ΔU = 5RΔT/2.
6. For an ideal diatomic gas, internal energy depends primarily on which quantity?
A.
Temperature
B.
Pressure only
C.
Volume only
D.
Shape of the container
Correct Answer:
Temperature
Explanation:
The internal energy of an ideal gas is a function of temperature only. For a diatomic gas, U = (5/2)nRT under the usual ordinary-temperature approximation.
7. If the absolute temperature of a fixed amount of an ideal diatomic gas is doubled, its internal energy becomes:
A.
Half its original value
B.
Unchanged
C.
Twice its original value
D.
Four times its original value
Correct Answer:
Twice its original value
Explanation:
For a fixed amount of an ideal diatomic gas, U = (5/2)nRT, so internal energy is directly proportional to absolute temperature.
8. Which two types of molecular motion contribute to the internal energy of an ideal diatomic gas at ordinary temperatures?
A.
Translational and rotational motion
B.
Rotational and vibrational motion only
C.
Translational and vibrational motion only
D.
Vibrational motion only
Correct Answer:
Translational and rotational motion
Explanation:
At ordinary temperatures, the 3 translational and 2 rotational degrees of freedom are active, while vibrational motion is usually neglected.
9. For 2 moles of an ideal diatomic gas heated through a temperature rise of ΔT, the increase in internal energy is:
A.
RΔT
B.
3RΔT
C.
5RΔT
D.
7RΔT
Correct Answer:
5RΔT
Explanation:
Using ΔU = nCvΔT with n = 2 and Cv = 5R/2, we get ΔU = 2 × 5R/2 × ΔT = 5RΔT.
10. At the same temperature, compared with one mole of an ideal monatomic gas, one mole of an ideal diatomic gas has:
A.
Less internal energy
B.
The same internal energy
C.
More internal energy
D.
Zero internal energy
Correct Answer:
More internal energy
Explanation:
At the same temperature, a monatomic gas has U = 3RT/2, while a diatomic gas has U = 5RT/2. Therefore, the diatomic gas has greater internal energy.
Short Questions and Answers
Practice short questions and answers related to
Diatomic Gas
.
Short questions are currently unavailable for this page.