Răspuns:
100g Mg.......................80g pur
8gMg................................xg pur
x=8×80/100=6,4g Mg pur
MMg=24g/mol
MMgO=24+16=40g/mol
2×24g..............2×40g
2Mg + O 2 → 2MgO
6,4g....................yg
y=6,4×2×40/2×24=10,67g MgO
Explicație: