Question

расставить коэффициенты Cr+O2=Cr2O3; C+H2=CH4; Zn+HBr=ZnBr2+H2

Answer 1

4 Cr + 3 O2 = 2 Cr2O3
C + 2 H2 = CH4
Zn + 2 HBr = ZnBr2 + H2

Answer 2

4cr+6o2=2cr2o3 
c+2H2=ch4
zn+2hbr=zndr2+h2