Question

It is found that the excitation frequency from ground to the first excited state of rotation for the CO molecule is close to $\frac{4}{\pi}\times10^{11}$ Hz. Then the moment of inertia of CO molecule about its centre of mass is close to (Take $h = 2\pi\times10^{-34}$ J -s)

• A. $2.76\times10^{-46} kg-m^2$
• B. $1.87\times10^{-46} kg-m^2$
• C. $4.67\times10^{-47} kg-m^2$
• D. $1.17\times10^{-47} kg-m^2$

Answer 1

Answer: (B)

$hv=K_2-K_1=\frac{3h^2}{8\pi^2I}$
$\therefore I=\frac{3h}{8\pi^2f}=\frac{3\times2\pi\times10^{-34}\times\pi}{8\times\pi^2\times4\times10^{11}}$
$=1.87\times10^{-46}kg-m^2$
$\therefore $ The correct answer is (b).