Question

When Metal ‘M’ is treated with NaOH, a white gelatinous precipitate ‘X’ is obtained, which is soluble in excess of NaOH. Compound ‘X’ when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal ‘M’ is ______.

Options

• Zn

• Ca

• Al

• Fe

Answer 1

When Metal ‘M’ is treated with NaOH, a white gelatinous precipitate ‘X’ is obtained, which is soluble in excess of NaOH. Compound ‘X’ when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal ‘M’ is Al.

Explanation:

When aluminium metal is treated with NaOH, it forms a white gelatinous precipitate of aluminium hydroxide, which dissolves in excess NaOH to form a soluble aluminate ion. Upon strong heating, this hydroxide gives alumina (Al₂O₃), which is a white oxide widely used as an adsorbent in chromatography. This unique behaviour helps identify metal ‘M’ as aluminium. Hence, Metal ‘M’ is Aluminium (Al).