From the question, it was given that the Uranium has a molar mass of 238 grams/mole. It means that for every mole of uranium, its mass will be 238 grams.
Because the question asks the mass of 3 moles of uranium, it will be 3 times the mass of a single mole of it. From this, we can perform the calculation as follows:
![\begin{gathered} 1\text{mole}\to238g \\ 3\text{moles}\to3*238g=714g \\ \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/cxg7gfejtd3aslifzu9xocnx5nzstat3it.png)
From the solution presented above, we are able to conclude that 3 moles of uranium weigh 714g.