A,He=4 A,H=1----> A,He= 4A,H----> 4 ATOMI
NUMARUL lui Avogadro
1u.a.m.= 1,66x10⁻²⁷kg
1u.a.m. 1,66x10⁻²⁴g
x..........................12g
x=7,2x10⁻²⁴u.a.m.