Question

Salts can be prepared by the action of dilute acid on:

1. bases
2. carbonates
3. metals
4. sulphites

The method which cannot be used for the preparation of copper salts is:

Options

• 1

• 2

• 3

• 4

Answer 1

3

Explanation:

Dilute acids produce salts on bases, carbonates and sulphites (for example, \[\ce{CuO + 2HCl → CuCl2 + H2O and acid + carbonate → salt + CO2 + H2O)}\], but the “metal + dilute acid → salt + H₂” route works only for active metals (Zn, Fe, Mg, etc.), not for copper. Copper does not displace H⁺ from dilute non‑oxidizing acids, so you cannot prepare copper salts by directly reacting copper metal with a dilute acid.