Which of the following compounds is sparingly soluble in ammonia?

Which of the following happens when $NH_{4}OH$ is added gradually to the solution containing $1 \ M \ A^{2+}$ and $1 \ M \ B^{3+}$ ions?
Given: $K_{sp}[A(OH)_{2}] = 9 \times 10^{-10}$ and $K_{sp}[B(OH)_{3}] = 27 \times 10^{-18}$ at $298 \ K$.

The solubility products of three sparingly soluble salts $AB$,$A_2B$ and $AB_3$ are respectively $4.0 \times 10^{-20}$,$3.2 \times 10^{-11}$ and $2.7 \times 10^{-31}$. The increasing order of their solubility is

The $K_{sp}$ of $AgBr$ at $25 \, ^\circ C$ is $4.9 \times 10^{-13}$. If the molar mass of $AgBr$ is $188 \, g/mol$,how much $AgBr$ is required to saturate $20 \, L$ of water?

The solubility of $BaSO_{4}$ in water is $2.42 \times 10^{-3} \ g \ L^{-1}$ at $298 \ K$. The value of solubility product $(K_{sp})$ will be (Given molar mass of $BaSO_{4} = 233 \ g \ mol^{-1}$)

Which of the following is least soluble in water?