 Solution

ID: past-exam-of-the-chemistry-a-course-of-the-university-of-cambridge/2021/paper-1/a3/a/iv/solution

Using the stipulated integer isotope masses gives

μ = \frac{12 \times 32}{44} u = 8.72727 u, I = μ (1.53 \times 1 0^{- 10} m)^{2} = 3.39243 \times 1 0^{- 46} kg m^{2} .

B = \frac{h}{8 π ^{2} c I} = 0.8252 c m^{- 1} .

Here

c

must be expressed in

cm s^{- 1}

when

I

is in SI units. Equivalently calculate

B = h / (8 π^{2} I)

Hz

first, then divide by

c

cm s^{- 1}

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