c
\(A _{2} X _{3( s )} \rightleftharpoons 2 A _{( aq )}^{+3}+3 X _{( aq )}^{-2}\)

solubility \(= sM\quad 2 s \quad 3 s\)

\((2 s )^{2}(3 s )^{3}=1.1 \times 10^{-23}\)

\(108 s ^{5}=1.1 \times 10^{-23}\)

\(s \simeq 10^{-5} M =10^{-5} \,\frac{ mol }{ L }=0.01 \,\frac{ mol }{ m ^{3}}\)

Now \(\wedge_{ m } \simeq \wedge_{ m }^{\infty}=\frac{ k }{ m }=\frac{ k }{ s }\)

\(\Rightarrow \wedge_{ m }^{\infty}=\frac{3 \times 10^{-5}}{0.01}=3 \times 10^{-3} \,S - m ^{2} / mol\)

Ans. \(3\)