Answer
$4.29\text{ kg}$
Work Step by Step
First we calculate the volume:
$\text{Volume}=6.5\text{ cm}\times 9.0\text{ cm}\times 3.25\text{ cm}=190.125\text{ cm}^3$
Then we calculate the mass, using the density of Osmium $22.59\text{ g/cm}^3$:
$\text{Mass}=190.125\text{ cm}^3\times 22.59\text{ g/cm}^3\approx 4294.93\text{ g}$
Convert to kilograms:
$4294.93\text{ g}\div 1000\approx 4.29\text{ kg}$
