Soluble salts can be prepared by the following methods except

Analyze the question: We need the method that is NOT used to prepare soluble salts. Three of the four options are standard ways to make soluble salts, and one is not.

Concept: Methods of preparing salts

• Soluble salts (e.g., Na₂SO₄, ZnSO₄, NaCl, KNO₃) are made by: • Acid + base/alkali (neutralization) • Acid + carbonate (trioxocarbonate(IV)) • Acid + reactive metal • Acid + metal oxide
• Insoluble salts (e.g., BaSO₄, PbCl₂, AgCl, CaCO₃) are made by double decomposition (precipitation), where two soluble salts react to form an insoluble salt.

Step by step check:

• A. Neutralization: HCl + NaOH → NaCl + H₂O. This gives a soluble salt, so it is a valid method.
• B. Acid + trioxocarbonate(IV) salt: Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂. This gives a soluble salt, so it is valid.
• C. Double decomposition: AgNO₃ + NaCl → AgCl↓ + NaNO₃. The aim is to precipitate an insoluble salt, so it is mainly used for insoluble salts. Although a soluble salt (NaNO₃) is also formed in solution, the method is characteristically the one for preparing insoluble salts.
• D. Acid + electropositive metal: Zn + H₂SO₄ → ZnSO₄ + H₂. This gives a soluble salt, so it is valid.

Tip: Remember the pairing: soluble salts → acid reactions (with bases, carbonates, metals); insoluble salts → double decomposition (precipitation). If a WASSCE question says "except" and lists double decomposition, it usually refers to this contrast.