alleryWhat is the molar specific heat at constant pressure of helium treated as an ideal gas?
- (5/2) R
- (3/2) R
- (7/2) R
- 3 R
Show answer and solution
Correct answer: A. (5/2) R
Cp is Cv plus R, and for a monatomic gas that is (3/2) R + R = (5/2) R.
CBSE Class 11 (Science) Kinetic Theory & Oscillations — practice questions — page 4
Explore 180 free Kinetic Theory & Oscillations questions in CBSE Class 11 (Science) Physics. Open each question or exercise to read its content, reference answers and available explanation.
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What is the molar specific heat at constant pressure of helium treated as an ideal gas?Read the answer and worked solution →What is the ratio of specific heats γ for a rigid diatomic ideal gas?Read the answer and worked solution →A diatomic gas also has one active vibrational mode. What is its molar Cv?Read the answer and worked solution →A polyatomic molecule has 3 translational, 3 rotational and f vibrational modes. Molar Cv?Read the answer and worked solution →For any ideal gas, the difference Cp - Cv between molar specific heats equalsRead the answer and worked solution →Why do measured specific heats of Cl2 exceed rigid-model values?Read the answer and worked solution →How much heat raises 1 mol of argon by 20 K at constant volume? (R = 8.31 J/mol K)Read the answer and worked solution →What is the internal energy of 2 mol of helium at 300 K? (R = 8.31 J/mol K)Read the answer and worked solution →Why are Cp and Cv nearly equal for a solid?Read the answer and worked solution →What is meant by the mean free path of a gas molecule?Read the answer and worked solution →How does the mean free path depend on the molecular diameter d?Read the answer and worked solution →Gas pressure is doubled at constant temperature. What happens to the mean free path?Read the answer and worked solution →Why does gas from a leak spread slowly through a room?Read the answer and worked solution →What is the approximate mean free path of air molecules at STP?Read the answer and worked solution →Why do air molecules in a room not all settle on the floor under gravity?Read the answer and worked solution →Where does a gas in equilibrium in a container exert pressure?Read the answer and worked solution →Treating water molecules as closely packed in liquid water, the estimated molecular radius is aboutRead the answer and worked solution →Average distance between molecules of water vapour at 100 °C and 1 atm is aboutRead the answer and worked solution →Water vapour at 100 °C and 1 atm has density 0.6 kg/m³. Fraction of volume filled by molecules?Read the answer and worked solution →Who proposed that equal gas volumes at equal T and P have equal molecule numbers?Read the answer and worked solution →A gas's molecules carry translational KE of 1.5 × 10^5 J per cubic metre. Its pressure isRead the answer and worked solution →Ignoring vibrations, what is γ = Cp/Cv for a nonlinear polyatomic ideal gas?Read the answer and worked solution →Who published Hydrodynamica in 1738, laying the basis for the kinetic theory of gases?Read the answer and worked solution →Which physicist introduced the concept of the mean free path in 1857?Read the answer and worked solution →Einstein (1905) and Smoluchowski (1906) supported kinetic theory with papers onRead the answer and worked solution →Which Roman philosopher, around 50 BC, said static bodies are made of rapidly moving atoms?Read the answer and worked solution →Which physicist generalised Maxwell's velocity distribution in 1871?Read the answer and worked solution →Kinetic theory assumes the total volume of the molecules themselves isRead the answer and worked solution →In SHM, how does the restoring force depend on the displacement?Read the answer and worked solution →In SHM, the restoring force always acts in which direction?Read the answer and worked solution →
Worked practice questions
What is the ratio of specific heats γ for a rigid diatomic ideal gas?
- 1.67
- 1.29
- 1.40
- 1.33
Show answer and solution
Correct answer: C. 1.40
Five degrees of freedom give Cv = (5/2)R and Cp = (7/2)R, so γ = 7/5 = 1.40.
A diatomic gas also has one active vibrational mode. What is its molar Cv?
- (5/2) R
- 3 R
- (9/2) R
- (7/2) R
Show answer and solution
Correct answer: D. (7/2) R
The vibration adds kB T per molecule on top of (5/2) kB T, so U = (7/2) RT per mole and Cv = (7/2) R.
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