a.
2moli Al2O3
m Al2O3
n=m: M
m=n.M
m=2moli . 102 g/moli=204 g Al2O3
M=2.27 + 3.16=102-------> 102g/moli
b.
1mol Al2O3--------6,023.10²³ molecule
xmoli--------------12,046. 10²³ molecule
x=12,046.10²³ : 6,023.10²³=2 moli Al2O3
m=2moli. 102g/moli=204g Al2O3
c.
0,5 kg=500 g Al2O3