SSC GD 2025 PYQ — Question 28

The correct answer is option 4 i.e. Na₂SO₄ (aq) + BaCl₂ (aq) → BaSO₄ (s) + 2NaCl (aq).

 

This reaction is a double displacement reaction, also called a precipitation reaction. In it, the ions of two compounds exchange places — Ba²⁺ from barium chloride combines with SO₄²⁻ from sodium sulfate to form barium sulfate (BaSO₄), an insoluble white precipitate, while Na⁺ and Cl⁻ form sodium chloride in solution.

Other options:

• Fe + CuSO₄ → FeSO₄ + Cu: Single displacement.

• MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O: Redox reaction.

• 2HNO₃ + Ca(OH)₂ → Ca(NO₃)₂ + 2H₂O: Neutralization, not double displacement.