Răspuns:
Explicație:
1.
n= 30115.10²³ : 6,022 10²³= 5000 moli He
n=m : M
m= n . M
m= 5000moli .4g/moli= 20000 g He
2.
m=n . M
m= 2moli . 24g/moli= 48g Mg
3.
n=m : M
n= 560g : 56g/moli=10moli Fe
4.
300 m moli= 0,3 moli Ca
1mol Ca ----------6,022.10 ²³atomi Ca
0,3 moli ----------------x
x= 0,3 . 6,022.10²³atomi Ca= 1,8066.10²³atomi Ca
5.
m= n. M
m= 100moli .39g/moli= 3900 g K
