Chapter 11, Problem 11B.10BE

(i)

Interpretation Introduction

Interpretation:

The most populated level at $25°\text{C}$ for ${\text{Br}}_{\text{2}}$ has to be stated.

Concept introduction:

A rotational spectrum is a spectrum in which only the rotation of molecule changes.  The energy for a rotational spectrum relates the quantum number and rotational constant to give the expression as shown below.

    $E=\tilde{B}J(J+1)$

In a rotational spectrum, there are levels.  The population of these levels increases with the increasing value of degeneracy.  According to Boltzmann distribution, the population decreases on increasing the levels.  Thus, to combine these two traits, there exists a maxima population.  The level at which the population is maximum is represented by $J_{\max }$.

(ii)

Interpretation Introduction

Interpretation:

The most populated level at $100°\text{C}$ for ${\text{Br}}_{\text{2}}$ has to be stated.

Concept introduction:

The concept introduction is same as discussed in part (i).