\(\mathrm{CuS} \rightleftharpoons \mathrm{Cu}^{2+}+\mathrm{S}^{2-}, K_{\mathrm{sp}}=6 \times 10^{-16}\)
Maximum molarity of \(\mathrm{CuS}\) in aqueous solution means solubility of CuS.
Let the solubility of CuS be \(S \mathrm{~mol} \mathrm{~L} \mathrm{~L}^{-1}\)
\(\begin{aligned}
&\therefore \quad K_{\text {sp }}=\left[\mathrm{Cu}^{2+}\right][\mathrm{S}]^{2-} \\
&\quad 6 \times 10^{-16}=S \times S=S^2 \\
&\therefore S=\sqrt{6 \times 10^{-16}}=2.45 \times 10^{-8} \mathrm{~mol} \mathrm{~L}^{-1} .
\end{aligned}\)
Hence, maximum molarity \(=2.45 \times 10^{-8} \mathrm{~mol} \mathrm{~L}^{-1}\)