а) Mn(NO₃)₂ + Ba(OH)₂ = Mn(OH)₂↓ + Ba(NO₃)₂
Mn²⁺ + 2NO₃⁻ + Ba²⁺ + 2OH⁻ = Mn(OH)₂↓ + Ba²⁺ + 2NO₃⁻
Mn²⁺ + 2OH⁻ = Mn(OH)₂↓
б) Na₂S + H₂SO₄ = Na₂SO₄ + H₂S↑
2Na⁺ + S²⁻ + 2H⁺ + SO₄²⁻ = 2Na⁺ + SO₄²⁻ + H₂S↑
S²⁻ + 2H⁺ = H₂S↑
в) 2KOH + CO₂ = K₂CO₃ + H₂O
2K⁺ + 2OH⁻ + CO₂ = 2K⁺ + CO₃²⁻ + H₂O
2OH⁻ + CO₂ = CO₃²⁻ + H₂O
г) Ni(OH)₂ + 2HCI = NiCI₂ + 2H₂O
Ni²⁺ + 2OH⁻ + 2H⁺ + 2CI⁻ = Ni²⁺ + 2CI⁻ + 2H₂O
2OH⁻ + 2H⁺ = 2H₂O