folosesc relatiile
n sau niu= V/V,m n sau niu= N/N,Avogadro
a. V=7000l V/V,m=N/N.A
7000/22,4= N/6,023X10²³-------------------------->calculeaza N
b. pV=niuRT
3X7000=niux0,082x(273+27) calculeaza niu sau n
niu=N/6,023x10²³ ; niu e calculat deja, acum calculeaza N