${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3+{\mathrm{NH}}_4\mathrm{OH}⟶\mathrm{X}$. Select the correct statement(s) about compound $\mathrm{X}$.

What will be the hybridization in compound $\left(\mathrm{A}\right)$ (this question is from the book does not give details and is incorrect. Hence, it has been reframed along with options). An unknown compound (A) when treated with concentrated sulphuric acid, gives light brown fumes which intensify on the addition of copper turnings. When an aqueous solution of the compound is treated with freshly prepared ${\mathrm{FeSO}}_4$, followed by concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$, it yields a brown complex at the junction of the two liquids. When the compound is heated with sodium hydroxide solution, it evolves a colourless pungent gas. In another test tube, the solution of the compound is mixed with Nessler's reagent to form a brown precipitate. What is the hybridization of the compound (A)?

${\mathrm{CaCO}}_3\stackrel{\mathrm{\Delta }}{⟶}\mathrm{A}+\mathrm{B} \left(\mathrm{g}\right)$

$\mathrm{A}+{\mathrm{H}}_2\mathrm{O}⟶\mathrm{C}$

$\mathrm{C}+\mathrm{B}⟶\underset{\left(\mathrm{white} \mathrm{precipitate}\right)}{\mathrm{D}}+{\mathrm{H}}_2\mathrm{O}$

$\mathrm{D}+\mathrm{B} \left(\mathrm{g}\right)\to \underset{\left(\mathrm{water} \mathrm{soluble}\right)}{\mathrm{E}}\underset{{\mathrm{BaCl}}_2}{\stackrel{\mathrm{Boil}}{\to }}\underset{(\mathrm{white} \mathrm{precipitate})}{\mathrm{F}}$

Note: Question details are changed from that of the book.

Select the correct option(s) for the white precipitate shown in the above reactions.