When metal X is treated with sodium hydroxide ,a white precipate A is formed ,which is soluble in excess ofsodium hydroxide to give soluble complex B ,compound A is soluble in HCl to form compound C ,the compound A when heated strongly give D ,which is used to extract metal.Write A,B,C,D.Write suitable equation to support their identity

The given metal X gives a white precipitate with sodium hydroxide and the

precipitate dissolves in excess ofsodium hydroxide. Hence, X must be

aluminium.

The white precipitate(compound A) obtained is aluminium hydroxide. The

compound B formed when an excess of the base is added is sodium

tetrahydroxoaluminate(III)

.

Now, when dilute hydrochloric acid is added to aluminium hydroxide, aluminium

chloride (compound C) is obtained.

Also, when compound A is heated strongly, it gives compound D. This

compound is used to extract metal X. Aluminium metal is extracted from

alumina. Hence, compound D must be alumina.