Na2SO4
a) M=2ANa+AS+4AO=2*23+32+4*16
= 2*23+32+4*16=46+32+64=142
b) Ratomic=2:1:4
Rmasa=2ANa:AS:4AO=2*23:32:4*16= 46:32:64=23:16:32
c) 142 g.....46g,32g,64g
100 x y z
x=32,39 y=22,53 z=45,07
d) m=300 g
mS=?
mO=?
142 g 32gS..........64 gO
300 g x y
x=67,60 y=135,21