Souring milk would actually be a chemical change because it changed the properties alltogether. You can't change soured milk into it's original taste.
Dry and desert conditions
BaCl₂(aq) + Na₂SO₄(aq) = BaSO₄(s) + 2NaCl(aq)
Ba²⁺(aq) + 2Cl⁻(aq) + 2Na⁺(aq) + SO₄²⁻(aq) = BaSO₄(s) + 2Na⁺(aq) + 2Cl⁻(aq)
Ba²⁺(aq) + SO₄²⁻(aq)= BaSO₄(s)
Multiply by 1.8 and then add 32.
The correct answer here would be C.
