Boltzmann Distribution and Temperature Effects

Steps:

• The Boltzmann distribution plots probability density of molecular energies versus energy at fixed temperature.
• The curve's peak represents the most probable energy, which increases with temperature.
• Raising temperature spreads the distribution, shifting the peak rightward on the energy axis.
• Activation energy (Ea) is a threshold for reaction, often marked as a vertical line, but not the curve's maximum.

Why B is correct:

• The Maxwell-Boltzmann distribution's peak energy is (3/2)kT for 3D, so higher T moves the maximum to higher energies (right on the diagram).

Why the others are wrong:

• A: Higher T flattens the curve, decreasing peak height while conserving total area (normalization).
• C: X likely marks Ea as an energy barrier, but the line length indicates Ea value, not inherently "for the reaction" without reaction context.
• D: Y probably shows a reaction's energy change, but enthalpy (ΔH) is a difference, not a single line length in Boltzmann plots.

Final answer: B