When metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of NaOH to give soluble complex (B). Compound (A) is soluble in dilute HCl to form compound (C). The compound (A) when heated strongly gives (D), which is used to extract metal. Identify (X), (A), (B), (C) and (D). Write suitable equations to support their identities.

Explanation

To solve the problem step by step, we need to identify the metal (X), the compounds (A, B, C, and D), and write the relevant chemical equations.

### Step 1: Identify Metal X
- The question states that when metal X is treated with sodium hydroxide (NaOH), a white precipitate is formed.
- The metal that typically forms a white precipitate with NaOH is **Aluminium (Al)**.

**Hint:** Look for metals that form white precipitates with NaOH.

...