a
\(K _2 SO _4 \longrightarrow 2 K ^{+}+ SO _4{ }^{2-}\)

\(0.1 M \quad\quad 0.2 M \quad0.1 M\)

\(BaSO _4 \rightleftharpoons Ba ^{+2}+ SO _4{ }^{2-}\)

\(a - S \quad S \quad S +0.1 \approx 0.1\)

\(K _{ SP }= S \times 10^{-1}\)

\(\Rightarrow 1 \times 10^{-10}= S \times 10^{-1}\)

\(\Rightarrow S =10^{-9} mol L^{-1 }\)

So, \(S =10^{-9} \times 233\,g\,L ^{-1}\)

So, Answer : \(233\)