Answer
It is not possible to construct this baryon using the up, down, and strange quarks only.
Work Step by Step
If the strangeness of the baryon is $-2$, then there must be two strange quarks, each with strangeness $-1$
The strange quark $s$ has charge $-\frac{1}{3}$, strangeness $-1$, and baryon number $+\frac{1}{3}$
Note that the net charge of two strange quarks is $-\frac{2}{3}$
We can only use one more quark since the baryon number of a baryon is $+1$
However, there is no way to make a net charge of $+1$ with only one more quark.
Therefore, it is not possible to construct this baryon using the up, down, and strange quarks only.
