6.
You have a system of non-interacting particles that can exist in three possible states, with
energy 0, E, 2E (E > 0). At a temperature T = E/kB (where kB = Boltzmann’s constant)
the energy states are occupied in approximately the ratio
a. 1 : 1 : 1
b. 1 : 0.5 : 0.25
c. 1 : 2.72 : 7.39
d. 1 : 0.37 : 0.14

The correct answer is d. 1 : 0.37 : 0.14.

Boltzmann Distribution Basics

Non-interacting particles follow the Boltzmann distribution, where occupation probability for state i is proportional to e-Ei / kBT. Here, energies are E0 = 0, E1 = E, E2 = 2E, and T = E / kB, so βE = 1 where β = 1 / kBT.

Normalized occupations are n0 : n1 : n2 = e0 : e-1 : e-2 = 1 : 0.37 : 0.14.

Option Analysis

  • a. 1 : 1 : 1 assumes equal populations, valid only at infinite temperature (kBT ≫ E) where Boltzmann factors approach 1.
  • b. 1 : 0.5 : 0.25 implies linear energy dependence, not exponential as required by Boltzmann statistics.
  • c. 1 : 2.72 : 7.39 reverses the trend (higher energy, more occupation), impossible since e-E/kBT < 1 for E > 0.
  • d. 1 : 0.37 : 0.14 matches e-1 ≈ 0.37 and e-2 ≈ 0.14, confirmed by partition function Z = 1 + e-1 + e-2 ≈ 1.50.

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Introduction to Non-Interacting Particles Three Energy States Occupation Ratio

In statistical mechanics for CSIR NET Life Sciences, understanding the non-interacting particles three energy states occupation ratio at T = E/kB is crucial for Boltzmann distribution applications. This MCQ tests equilibrium populations across energies 0, E, 2E (E > 0). The correct ratio follows exponential decay, vital for thermodynamics and biophysical chemistry.

Detailed Boltzmann Calculation

Particles occupy states per ni ∝ gie-Ei / kBT, assuming non-degenerate levels (gi = 1). At T = E/kB:

  • n0 ∝ 1
  • n1 ∝ e-1 ≈ 0.3679
  • n2 ∝ e-2 ≈ 0.1353

Ratio: 1 : 0.37 : 0.14. Partition function Z ≈ 1.503 confirms normalization.

Why Other Options Fail in CSIR NET Context

Option Ratio Reason for Incorrectness
a 1:1:1 High-T limit only (kBT >> 2E)
b 1:0.5:0.25 Linear, ignores exponential Boltzmann factor
c 1:2.72:7.39 Inverted (e+E/kBT), violates energy minimization
d 1:0.37:0.14 Matches e-E/kBT exactly

CSIR NET Exam Tips

Practice similar questions on canonical ensemble and partition functions. For non-interacting particles, always compute ratios relative to ground state. This concept links to protein folding energetics and enzyme kinetics in life sciences.

 

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