A colourless solution gives a white gelatinous precipitate with NaOH that dissolves in excess NaOH. With NH4OH (in the presence of NH4Cl) the white precipitate does not dissolve in excess. The cation, among the following, is

JEE Main levelSingle correct optionDifficulty 2 of 3qc137

A colourless solution gives a white gelatinous precipitate with $NaOH$ that dissolves in excess $NaOH$ . With $NH X_{4} OH$ (in the presence of $NH X_{4} Cl$ ) the white precipitate does not dissolve in excess. The cation, among the following, is

Al (OH) X_{3}

is amphoteric, dissolving in excess alkali as

[Al (OH) X_{4}] X^{-}

, and is insoluble in excess ammonia.

Zn (OH) X_{2}

would also dissolve in excess ammonia by forming

[Zn (NH X_{3}) X_{4}] X^{2 +}

Mg (OH) X_{2}

does not dissolve in

NaOH

, and

Fe (OH) X_{3}

is brown.