MHT CET202526 Apr 2025Morning ShiftChemistryIonic EquilibriumActual
Which among the following salt turns blue litmus red in its aqueous solution?
Options
- ACuSO ₄
- BNa ₂ CO ₃
- CNa ₂ SO ₄
- DNaNO ₃
Correct answer
A. CuSO ₄
Step-by-step solution
Identification of acidic salt The salt that turns blue litmus red must yield an acidic aqueous solution through hydrolysis of its constituent ions. Copper(II) sulfate ( CuSO4 ) dissociates into Cu²⁺ and SO₄²⁻ ions. The Cu²⁺ cation, being the conjugate acid of weak base Cu(OH)₂ , hydrolyzes: Cu²⁺ + 2H₂ O Cu(OH)₂ + 2H+ This reaction produces hydrogen ions, acidifying the solution. Sodium carbonate ( Na₂CO₃ ) yields basic solution due to CO₃²⁻ hydrolysis: CO₃²⁻ + H₂ O HCO₃- + OH- . Sodium sulfate ( Na₂SO₄ ) and sodium