Answer
For quark composition $ssd$, we have $$Q=-\frac{1}{3}-\frac{1}{3}-\frac{1}{3}=-1 $$
and $$S=-1-1+0=-2 $$
Therefore this is a $\Xi^{-}$
Work Step by Step
For quark composition $ssd$, we have $$Q=-\frac{1}{3}-\frac{1}{3}-\frac{1}{3}=-1 $$
and $$S=-1-1+0=-2 $$
Therefore this is a $\Xi^{-}$
