Sửa đề : 24.8 (g) Na2O
\(n_{Na_2O}=\dfrac{24.8}{62}=0.4\left(mol\right)\)
\(n_{HNO_3\left(dư\right)}=\dfrac{50.4}{63}=0.8\left(mol\right)\)
\(Na_2O+2HNO_3\rightarrow2NaNO_3+H_2O\)
\(0.4............0.8..............0.8...........0.4\)
\(m_{NaNO_3}=0.8\cdot85=68\left(g\right)\)
\(m_{H_2O}=0.4\cdot18=7.2\left(g\right)\)