MN203 = 28+48 = 76
76 - 100%
28 - x
x= 2800/78 = 36 %
19 - 100%
x - 36
x= 19*36 / 100
x=6.84 g
MN2O5 = 28+ 80 = 108
108 - 100%
28 - x
x= 2800/108 = 26
27 - 100%
x - 26
x = 27*26 / 100
x= 7.02
2.
7:6
7+6=13
13 - 100%
7 - x
x = 700/13
x= 53.8
Fe = 53.8%
S= 46.2 %
3.
x 54g
2Al + 3FeO -> Al2O3 + 3Fe
54 216
x/54 = 54/216
x = 54*54/216
x = 13.5