H2CO3 = Mr = H2CO3 = 1 x 2 + 12 x 1 + 16 x 3 = 62
H2 = 1 x 2 / 62 x 100 = 3
C = 12 x 1 / 62 x 100 = 19
O3 = 16 x 3 / 62 x 100 = 77
62 + 3 + 19 + 77 = 161
H2SO4 = Mr = H2SO4 = 1 x 2 + 32 x 1 + 16 x 4 = 98
H2 = 1 x 2 / 98 x 100 = 2
S = 32 x 1 / 98 x 100 = 32
O4 = 16 x 4 / 98 x 100 = 65
98 + 2 + 32 + 65 = 197
CaCO3 = Mr = 40 x 1 + 12 x 1 + 16 x 3 = 100
Ca = 40 x 1 / 100 x 100 = 40
C = 12 x 1 / 100 x 100 = 12
O3 = 16 x 3 / 100 x 100 = 48
100 + 40 + 12 + 48 = 200
K2CO3 =
P2O3 =