-SE CALCULEAZA MASA MOLARA ,M, care ne indica cat cantareste 1 mol
M=(2x27gAl + 3x16gO)/mol=102g/mol
-deduci masa celor 0,4moli
1mol........102g
0,4mol......m= calculeaza >>>>>>>>...
-acum faci tu acelasi rationament , dar transfori molii in kmoli, stiind ca 1kmol=1000mol