Answer
200 amu
Work Step by Step
Chromium (III) sulfide has a molecular formula equal to $Cr_2S_3$. The molecular mass of the compound is obtained through the atomic masses of the elements (Cr and S) and by the number of atoms of each element.
Therefore,
MM ($Cr_2S_3$) =$(2\times52)+(3\times32) =200amu$
Note: 200 amu or 200 u, these are similar nomeclatures.
