A)MH2O=2+16=18g/mol
18gH2O...2gH...16gO
100gH2O...x...y
x=100*2/18
x=11,11%H
y=100*16/18
y=88,88%O
B)MH2SO4=2+32+64=98g/mol
98gH2SO4...2gH...32gS...64gO
100gH2SO4...x.........y............y
x=100*2/98
x=2,04%H
y=100*32/98
y=32,65%S
z=100*64/98
z=65,30%O
C)CaCO3
MCaCO3=35,5+12+32=79,5g/mol
79,5gCaCO3...35,5gCa...12gC...32gO
100gCaCO3........x...............y.........z
x=100*35,5/79,5
x=44,65%Ca
y=100*12/79,5
y=15,09%C
z=100*32/79,5
z=40,25%O
