c) n=m/M=>m=n*M=2*23=46g Na
MNaOH = ANa+AO+AH = 23+16+1=40g/mol
In 40g NaOH se gasesc....................23g Na
xg.......................................................46g Na
x=46*40/23=80g NaOH
d) Am aflat M-masa moleculara la c) pentru NaOH = 40g/mol
Aplicam formula n=m/M=>m=n*M=4*40=160g NaOH