If ${\mathrm{X}}_{\mathrm{M}}, {\mathrm{X}}_{\mathrm{P}}$ and ${\mathrm{X}}_{\mathrm{V}}$ are mole fraction, pressure fraction and volume fraction, respectively, of a gaseous mixture, then:

Two bulbs $\mathrm{A}$ and $\mathrm{B}$ of equal capacity are filled with $\mathrm{He}$ and ${\mathrm{SO}}_2$, respectively, at the same temperature. If the pressure in two bulbs is same, calculate the ratio of ${\mathrm{V}}_{\mathrm{rms}}$ for them.