Em tham khảo nha :
\(\begin{array}{l}
CTHH:N{a_2}S{O_4}\\
M = 2{M_{Na}} + {M_S} + 4{M_O} = 23 \times 2 + 32 + 16 \times 4 = 142dvC\\
\% Na = \dfrac{{2{M_{Na}}}}{M} \times 100\% = \dfrac{{2 \times 23}}{{142}} \times 100\% = 32,39\% \\
\% S = \dfrac{{{M_S}}}{M} \times 100\% = \dfrac{{32}}{{142}} \times 100\% = 22,54\% \\
\% O = \dfrac{{4{M_O}}}{M} \times 100\% = \dfrac{{4 \times 16}}{{142}} \times 100\% = 45,07\%
\end{array}\)