Em tham khảo nha :

\(\begin{array}{l}
7)\\
a)\\
Mg + 2HCl \to MgC{l_2} + {H_2}\\
b)\\
{n_{Mg}} = \dfrac{{2,4}}{{24}} = 0,1mol\\
{n_{{H_2}}} = {n_{Mg}} = 0,1mol\\
{V_{{H_2}}} = 0,1 \times 22,4 = 2,24l\\
c)\\
{n_{HCl}} = 2{n_{Mg}} = 0,2mol\\
{m_{HCl}} = 0,2 \times 36,5 = 7,3g\\
C{\% _{HCl}} = \dfrac{{7,3}}{{50}} \times 100\%  = 14,6\% \\
8)\\
a)\\
N{a_2}C{O_3} + 2HCl \to 2NaCl + C{O_2} + {H_2}O\\
{n_{N{a_2}C{O_3}}} = \dfrac{{10,6}}{{106}} = 0,1mol\\
{n_{C{O_2}}} = {n_{N{a_2}C{O_3}}} = 0,1mol\\
{V_{C{O_2}}} = 0,1 \times 22,4 = 2,24l\\
{n_{HCl}} = 2{n_{N{a_2}C{O_3}}} = 0,2mol\\
{m_{HCl}} = 0,2 \times 36,5 = 7,3g\\
{m_{{\rm{dd}}HCl}} = \dfrac{{7,3 \times 100}}{{10}} = 73g\\
b)\\
{n_{NaCl}} = 2{n_{N{a_2}C{O_3}}} = 0,2mol\\
{m_{NaCl}} = 0,2 \times 58,5 = 11,7g\\
C{\% _{NaCl}} = \dfrac{{11,7}}{{10,6 + 73 - 0,1 \times 44}} \times 100\%  = 14,8\% 
\end{array}\)