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A Levels Chemistry (9701)•9701/11/M/J/20
Question 6 from 9701/11/M/J/20

Explanation

Boltzmann Distribution Peak at Lower Temperature

Steps:

  • Identify the curve for the lower temperature: it shifts left with a higher peak at lower energies compared to the higher temperature curve.
  • Recall that the most probable energy is the mode, the energy at the curve's maximum probability.
  • Locate the peak on the lower temperature curve in the diagram.
  • Match the peak position to the labeled point C.

Why C is correct:

  • C marks the maximum of the lower temperature distribution, where the probability density function f(E)∝E2e−E/kTf(E) \propto E^2 e^{-E/kT}f(E)∝E2e−E/kT peaks, defining the most probable energy by the Boltzmann distribution.

Why the others are wrong:

  • A: Marks the peak of the higher temperature curve, which has a lower peak at higher energy.
  • B: Lies on the low-energy tail of the lower temperature curve, not the maximum.
  • D: Lies on the high-energy tail of the lower temperature curve, beyond the peak.

Final answer: C

Topic: Reaction kinetics

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