Error:
As2O3 %2B Zn %2B HCl %3D ZnCl2 %2B AsH3 %2B H2O
^
Unexpected character ('%')As2O3 %2B Zn %2B HCl %3D ZnCl2 %2B AsH3 %2B H2O
^
Unexpected character ('%')