Дано:
m(Na)-4.6г
m(H2O)-150г

W(р.вещ.)-?

2Na+2H2O=2NaOH+H2n(Na)=n(NaOH)=4.6/23=0.2m(NaOH)=0.2*40=8m(p)=4.6+150-0.2=154.4w=8/154.4*100%=5.18%