Internal Energy NEET Questions

Physics - Thermodynamics

Internal Energy MCQ Questions


1.
The internal energy of a thermodynamic system is defined as:
A.
The kinetic energy of the system as a whole moving with velocity v
B.
The sum of kinetic and potential energies of all molecular constituents in the frame where the centre of mass is at rest
C.
Only the translational kinetic energy of gas molecules
D.
The work done by the system on surroundings
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ANSWER :
B. The sum of kinetic and potential energies of all molecular constituents in the frame where the centre of mass is at rest
2.
Internal energy U is described in NCERT as the energy associated with:
A.
The gravitational potential energy of the system
B.
The random (disordered) molecular motion and intermolecular potential energy
C.
The pressure exerted by the system on its container
D.
The ordered motion of the system's centre of mass
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ANSWER :
B. The random (disordered) molecular motion and intermolecular potential energy
3.
Which types of molecular motion contribute to the internal energy U of a gas? (NCERT Fig 11.3)
A.
Only rotational and vibrational motion
B.
Only electronic energy
C.
Only translational motion
D.
Translational, rotational, and vibrational kinetic energy — all forms of random molecular motion
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ANSWER :
D. Translational, rotational, and vibrational kinetic energy — all forms of random molecular motion
4.
In NCERT Fig 11.3, a box of gas is shown (a) at rest and (b) moving as a whole with velocity v. The internal energy U of the gas:
A.
Doubles when box velocity doubles
B.
Increases when the box moves faster
C.
Decreases when the box moves with velocity v
D.
Is the same in both cases — U depends only on the disordered molecular motion, NOT on the ordered bulk motion of the box
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ANSWER :
D. Is the same in both cases — U depends only on the disordered molecular motion, NOT on the ordered bulk motion of the box
5.
The internal energy U of a system is an example of a thermodynamic 'state variable.' This means:
A.
U has a different value for each observer
B.
U depends on the path taken to reach the current state
C.
U depends only on the current equilibrium state of the system — not on how that state was achieved
D.
U changes continuously even in equilibrium
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ANSWER :
C. U depends only on the current equilibrium state of the system — not on how that state was achieved
6.
For an ideal gas, the internal energy U depends on:
A.
Volume and density only
B.
Temperature ONLY — since ideal gas has negligible intermolecular forces, U = sum of molecular KE = (f/2)nRT
C.
Pressure and volume only
D.
All three: pressure, volume, and temperature
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ANSWER :
B. Temperature ONLY — since ideal gas has negligible intermolecular forces, U = sum of molecular KE = (f/2)nRT