A diatomic molecule is formed by two atoms which may be treated as mass points  m₁ and m₂ joined by a massless rod of length r. Then the moment of inertia of molecule about an axis passing through centre of mass and perpendicular to the rod is :

• A

  zero

• B

  $\left({\mathrm{m}}_1+{\mathrm{m}}_2\right){\mathrm{r}}^2$

• C

  $\left(\frac{{\mathrm{m}}_1{\mathrm{m}}_2}{{\mathrm{m}}_1+{\mathrm{m}}_2}\right){\mathrm{r}}^2$

• D

  $\left(\frac{{\mathrm{m}}_1+{\mathrm{m}}_2}{{\mathrm{m}}_1{\mathrm{m}}_2}\right){\mathrm{r}}^2$