# If a box was filled with radon gas (density 9.73g/L), how many kilograms (kg) of radon are in the box?

$\rho , \text{ density}$ $=$ $\text{Mass"/"Volume}$, and thus $\text{mass"=rhoxx"volume}$. We know the density becuase it is quoted in the question. We have no idea of the volume of the box, and thus will remain ignorant of radon mass.