Em tham khảo nha:
Câu c là 331,8g dung dịch $H_2SO_4$ nha em
\(\begin{array}{l}
a)\\
CTHH:X{O_2}\\
{M_{X{O_2}}} = 11,5 \times 4 = 46g/mol\\
\Rightarrow {M_X} = 46 - 16 \times 2 = 14\;g/mol\\
\Rightarrow X:Nito(N)\\
CTHH:N{O_2}\\
b)\\
\% {m_N} = \dfrac{{14}}{{46}} \times 100\% = 30,43\% \\
c)\\
{M_2}{O_3} + 3{H_2}S{O_4} \to {M_2}{(S{O_4})_3} + 3{H_2}O\\
{m_{{\rm{dd}}}} = 10,2 + 331,8 = 342g\\
{m_{{M_2}{{(S{O_4})}_3}}} = 342 \times 10\% = 34,2g\\
{n_{{M_2}{O_3}}} = {n_{{M_2}{{(S{O_4})}_3}}} \Leftrightarrow \dfrac{{10,2}}{{2{M_M} + 16 \times 3}} = \dfrac{{34,2}}{{2{M_M} + 96 \times 3}}\\
\Rightarrow {M_M} = 27\,g/mol \Rightarrow M:Al\\
CTHH:A{l_2}{O_3}
\end{array}\)