Class 11 Physics · Chapter 6 · Test 2
First Law of Thermodynamics
38 MCQs This test covers internal energy and its link to temperature, the sign convention for heat and work, and work done as PΔV and the area under a P-V curve. It also covers the first law with its applications and numericals, isothermal and adiabatic processes, and reversible and irreversible processes.
38 questions · 30 min · 38 marks
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Sample questions
The first 5 of 38. Try each one, then tap to see the answer.
Question 1
The sum of all molecular energies (kinetic and potential) of a substance is called its:
- AInternal energy
- BHeat
- CWork
- DEntropy
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Answer: A
The total of all molecular kinetic and potential energies in a substance is its internal energy.
Question 2
The internal energy of an ideal gas system is essentially the:
- APotential energy of its molecules
- BTranslational kinetic energy of its molecules
- CGravitational energy of the container
- DChemical energy of the gas
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Answer: B
Ideal gas molecules exert no forces on each other so the internal energy is the translational kinetic energy of the molecules.
Question 3
The potential energy associated with the molecules of an ideal gas is:
- AVery large
- BNegative
- CZero
- DEqual to the kinetic energy
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Answer: C
Ideal gas molecules are mass points that exert no forces on each other so their potential energy is zero.
Question 4
The internal energy of an ideal gas is directly proportional to its:
- APressure
- BVolume
- CDensity
- DAbsolute temperature
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Answer: D
Internal energy is the total molecular kinetic energy which depends only on absolute temperature for an ideal gas.
Question 5
According to the kinetic theory the average kinetic energy of a gas molecule is:
- A(3/2) k_B T
- Bk_B T^2
- C(3/2) R
- Dk_B / T
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Answer: A
The average translational kinetic energy per molecule is (3/2) k_B T.
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