Error:
H2O2 %2B H%3A%2B %2B MnO4%3A- %3D H2O %2B O2 %2B Mn%3A2%2B
^
Unexpected character ('%')H2O2 %2B H%3A%2B %2B MnO4%3A- %3D H2O %2B O2 %2B Mn%3A2%2B
^
Unexpected character ('%')