a)%mZnO=20% => %mCuO=100% - 20%=80%
b) mZnO=20%.25=5(g)=> nZnO=5/81(mol)
mCuO=25-5=20(g) => nCuO=20/80=0,25(mol)
PTHH: ZnO +2 HCl -> ZnCl2 + H2O
5/81_______10/81___5/81(mol)
CuO +2 HCl -> CuCl2 + H2O
0,25__0,5______0,25(mol)
=> nHCl=10/81 + 0,5=101/162(mol)
=>mHCl= 101/162 . 36,5=7373/324(g)
=> mddHCl= 7373/324 : 15%= 151,708(g)
=> VddHCl= 151,708/1,1=137,916(ml)