Sulphur and fluorine form ${\mathrm{SF}}_6$ and ${\mathrm{S}}_2{\mathrm{F}}_{10}$, both of which are gases at ${30}^{\circ }\mathrm{C}$. When an equimolar mixture of them is allowed to effuse through a pinhole, what is the ratio ${\mathrm{SF}}_6/{\mathrm{S}}_2{\mathrm{F}}_{10}$ in the first sample that escapes?

Molar mass	${\text{ g mol }}^{-1}$
${\mathrm{SF}}_6$	146
${\mathrm{S}}_2{\mathrm{F}}_{10}$	254