contestada

Redox Ex
20. Which reaction is an example of oxidation-reduction?
1) KOH + HCl → KCl + H₂O
2) 2 KCl → 2 K + Cl2
3) BaCl2 + K2SO4 → 2 KCl + BaSO4
4) KCl + AgNO3 → AgCl + KNO3