gamma_A is the specific heat ratio of monoatomic gas A having 3 translational degrees of freedom. gamma_B is the specific heat ratio of polyatomic gas B having 3 translational, 3 rotational degrees of freedom and 1 vibrational mode. If fracgamma_Agamma_B = left(1 + frac1nright) then the value of n is

Numerical Answer Type:
Enter a numerical value Answer: 3 to 3 +4 marks

Solution & Explanation

### Related Formula gamma = 1 + frac2f ### Core Logic Let's find the specific heat ratio for each gas based on degrees of freedom: 1. **Monoatomic gas A:** - Degrees of freedom, f_A = 3 (translational only) gamma_A = 1 + frac23 = frac53 2. **Polyatomic gas B:** - Translational degrees of freedom = 3 - Rotational degrees of freedom = 3 - Vibrational modes = 1. *Note: Each active vibrational mode has 2 degrees of freedom (kinetic + potential energy terms).* This contributes 2 times 1 = 2 degrees of freedom. - Therefore, the total active degrees of freedom is: f_B = 3 + 3 + 2 = 8 The specific heat ratio of B is: gamma_B = 1 + frac2f_B = 1 + frac28 = 1 + frac14 = frac54 Now, find the ratio of specific heat capacities: fracgamma_Agamma_B = frac5/35/4 = frac43 We are given: fracgamma_Agamma_B = 1 + frac1n implies frac43 = 1 + frac1n implies frac1n = frac13 implies n = 3 ### Step 1: Final Conclusion The value of n is 3. ### Pattern Recognition Always remember that each vibrational mode contributes exactly 2 degrees of freedom because it holds both kinetic and potential energy components (f_textvib = 2 times textmodes). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Kinetic Theory of Gases Class 11 Physics: Thermodynamics

Reference Study Guides

More Kinetic Theory of Gases Previous-Year Questions — Page 3

Q jee_main_2025_29_jan_morning Ideal Gas Laws
A container of fixed volume contains a gas at 27^circmathrmC . To double the pressure of the gas, the temperature of gas should be raised to _________ ^circmathrmC
Numerical Answer. Answer: 327 to 327

Solution

### Related Formula fracP_1T_1 = fracP_2T_2 ### Core Logic Initial temperature T_1 = 27 + 273 = 300text K. Since volume is kept fixed : fracP300 = frac2PT_2 implies T_2 = 600text K Converting back to Celsius : T_2 = 600 - 273 = 327^circmathrmC ### Chapter Mix Class 11 Physics: Kinetic Theory of Gases
Q36 jee_main_2024_01_february_morning Specific Heat Capacity
Two moles a monoatomic gas is mixed with six moles of a diatomic gas. The molar specific heat of the mixture at constant volume is:
  • A. frac94 R
  • B. frac74 R
  • C. frac32 R
  • D. frac52 R

Solution

### Related Formula Molar specific heat at constant volume for a gas mixture: C_Vtext, mix = fracn_1 C_V1 + n_2 C_V2n_1 + n_2 For a monoatomic gas: C_V1 = frac32R For a diatomic gas: C_V2 = frac52R ### Core Logic Given values: n_1 = 2 (monoatomic), n_2 = 6 (diatomic). Substitute these inputs directly into the mixture equation: C_Vtext, mix = frac2 times left(frac32Rright) + 6 times left(frac52Rright)2 + 6 ### Step 1: Simplify Expression C_Vtext, mix = frac3R + 15R8 = frac18R8 = frac94R ### Pattern Recognition Weighted average rule based on internal degrees of freedom: total internal energy changes scale additively with mole numbers. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Kinetic Theory of Gases Class 11 Physics: Thermodynamics
Q35 jee_main_2024_29_january_evening Ideal Gas Equation and Temperature
The temperature of a gas having 2.0 times 10^25 molecules per cubic meter at 1.38text atm (Given, k = 1.38 times 10^-23text J K^-1) is:
  • A. 500text K
  • B. 200text K
  • C. 100text K
  • D. 300text K

Solution

### Related Formula The state equation of an ideal gas in terms of the number of molecules N and Boltzmann constant k is: PV = NkT Rearranging to express pressure in terms of number density n = N/V: P = n k T ### Core Logic Given parameters: * Number density, n = fracNV = 2.0 times 10^25text molecules/m^3 * Pressure, P = 1.38text atm = 1.38 times 1.01 times 10^5text N/m^2 * Boltzmann constant, k = 1.38 times 10^-23text J K^-1 ### Step 1: Solve for Temperature Rearranging P = n k T for temperature T: T = fracPnk Substitute the values: T = frac1.38 times 1.01 times 10^5(2.0 times 10^25) times (1.38 times 10^-23) Notice that the term 1.38 cancels out from numerator and denominator: T = frac1.01 times 10^52.0 times 10^2 T = frac1.01 times 10^32.0 approx frac10102 approx 500text K ### Pattern Recognition The numerical values are designed to cancel out smoothly. Spotting the 1.38 cancelation instantly saves valuable calculation time. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Kinetic Theory of Gases
Q48 jee_main_2024_29_january_evening Degrees of Freedom and Specific Heat of Gas Mixtures
N moles of a polyatomic gas (f = 6) must be mixed with two moles of a monoatomic gas so that the mixture behaves as a diatomic gas. The value of N is:
  • A. 6
  • B. 3
  • C. 4
  • D. 2

Solution

### Related Formula The equivalent degrees of freedom f_texteq for a mixture of gases is: f_texteq = fracn_1 f_1 + n_2 f_2n_1 + n_2 where: * n_1, n_2 are the number of moles of each gas. * f_1, f_2 are the respective degrees of freedom of each gas. ### Core Logic For the given gases: 1. Polyatomic gas: * Moles, n_1 = N * Degrees of freedom, f_1 = 6 2. Monoatomic gas: * Moles, n_2 = 2 * Degrees of freedom, f_2 = 3 We want the mixture to behave as a diatomic gas. For a diatomic gas: * Equivalent degrees of freedom, f_texteq = 5 ### Step 1: Solve for N Substitute the values into the degrees of freedom mixture formula: 5 = frac(N)(6) + (2)(3)N + 2 5(N + 2) = 6N + 6 5N + 10 = 6N + 6 10 - 6 = 6N - 5N implies N = 4 ### Pattern Recognition Diatomic equivalent degree of freedom is 5. Since the monoatomic degrees of freedom (3) and polyatomic degrees of freedom (6) bracket 5, you can use the weighted ratio method to find the molar proportions directly. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Kinetic Theory of Gases
Q50 jee_main_2024_27_jan_morning Kinetic Energy and Temperature
The average kinetic energy of a monatomic molecule is 0.414text eV at temperature:
  • A. 3000text K
  • B. 3200text K
  • C. 1600text K
  • D. 1500text K

Solution

### Related Formula K_textavg = frac32 k_B T ### Core Logic Given energy is in electron-volts (1text eV = 1.6 times 10^-19text J), we isolate T: T = frac2 K_textavg3 k_B Substitute constants (k_B = 1.38 times 10^-23text J/K): ### Step 1: Compute value T = frac2 times 0.414 times 1.6 times 10^-193 times 1.38 times 10^-23 T = frac1.3248 times 10^-194.14 times 10^-23 = 0.32 times 10^4 = 3200text K ### Pattern Recognition Converting eV energy properties straight to structural SI standard Joules reveals highly cleanly simplified scalar components when paired with Boltzmann values. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Kinetic Theory of Gases

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