Start learning →

CG PET Specific Heats — practice questions

Explore 3 free Specific Heats questions in CG PET Physics. Open each question or exercise to read its content, reference answers and available explanation.

Practise Specific Heats with Quill →

Specific Heats questions and exercises with answers

Showing questions 1–3 of 3.

Mayer's relation for an ideal gas is:Read the answer and worked solution →For a monatomic ideal gas, $C_V$ and $C_P$ per mole are:Read the answer and worked solution →For a diatomic gas with all vibrational modes excited, the molar specific heat at constant volume is:Read the answer and worked solution →

Worked practice questions

Mayer's relation for an ideal gas is:

  1. $C_P - C_V = R$
  2. $C_P + C_V = R$
  3. $C_P \cdot C_V = R$
  4. $C_P / C_V = R$
Show answer and solution

Correct answer: A. $C_P - C_V = R$

**Mayer:** $C_P - C_V = R$ (per mole). Heat added at constant P goes to internal energy AND work (PΔV) at constant V, only internal energy. The difference equals the work term $PdV = RdT$ per mole.

Open this question →

For a monatomic ideal gas, $C_V$ and $C_P$ per mole are:

  1. $C_V = (3/2)R, C_P = (5/2)R$
  2. $C_V = (5/2)R, C_P = (7/2)R$
  3. $C_V = R, C_P = 2R$
  4. $C_V = 3R, C_P = 5R$
Show answer and solution

Correct answer: A. $C_V = (3/2)R, C_P = (5/2)R$

**Monatomic:** 3 DOF ⇒ Internal energy per mole = $(3/2)RT$ ⇒ $C_V = (3/2)R$. **By Mayer:** $C_P = C_V + R = (5/2)R$. $\gamma = 5/3 \approx 1.67$.

Open this question →

For a diatomic gas with all vibrational modes excited, the molar specific heat at constant volume is:

  1. $(3/2)R$
  2. $(5/2)R$
  3. $(7/2)R$
  4. $R$
Show answer and solution

Correct answer: C. $(7/2)R$

**DOF:** 3 trans + 2 rot + 2 vib (KE+PE) = 7. $C_V = (7/2)R$. $C_P = (9/2)R$. $\gamma = 9/7 \approx 1.29$. (At room temperature, vibrations are typically frozen out.)

Open this question →

How to practise

  1. Choose a Specific Heats question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

More Physics topics

MagnetismCurrent ElectricityWork and EnergyWork and PowerMagnetism and MatterElectromagnetismOpticsKinetic Theory of Gases