20/ The balanced equation for the reaction is:
2 KMnO4 → K2MnO4 + MnO2 + O2

21/ The balanced equation for the reaction is:
Fe + H2SO4 → FeSO4 + H2

22/ The balanced equation for the reaction is:
MnO2 + 4 HCl → MnCl2 + Cl2 + 2 H2O

23/ The balanced equation for the reaction is:
Ba(NO3)2 + H2SO4 → BaSO4 + 2 HNO3

24/ The balanced equation for the reaction is:
Fe(NO3)3 + 3 KOH → Fe(OH)3 + 3 KNO3

25/ The balanced equation for the reaction is:
BaO + 2 HBr → BaBr2 + H2O