Viết các phương trình hoá học biểu diễn các chuyển hoá sau

$$\begin{gathered} \mathrm{Viet} \mathrm{cac} \mathrm{phuong} \mathrm{trinh} \mathrm{hoa} \mathrm{hoc} \mathrm{bieu} \mathrm{dien} \mathrm{cac} \mathrm{chuyen} \mathrm{hoa} \mathrm{sau} \\ \mathrm{a}.{\mathrm{SO}}_3\stackrel{}{\to }{\mathrm{H}}_2{\mathrm{SO}}_4\stackrel{}{\to }{\mathrm{MgSO}}_4\stackrel{}{\to }\mathrm{Mg}{\left(\mathrm{OH}\right)}_2\stackrel{}{\to }\mathrm{MgO}\stackrel{}{\to }\mathrm{MgC}{1}_2 \\ \mathrm{b}.\mathrm{CaO}\stackrel{}{\to } \mathrm{Ca} {\left(\mathrm{OH}\right)}_2\stackrel{}{\to } {\mathrm{CaCO}}_3\stackrel{}{\to } \mathrm{CaC}{1}_2\stackrel{}{\to } \mathrm{Ca} \\ \mathrm{c}.\mathrm{A}1\stackrel{}{\to } \mathrm{A}{1}_2{\mathrm{O}}_3\stackrel{}{\to } \mathrm{A}1\mathrm{C}{1}_3\stackrel{}{\to } \mathrm{A}1{\left(\mathrm{OH}\right)}_3\stackrel{}{\to } \mathrm{A}{1}_2{\mathrm{O}}_3\stackrel{}{\to } \mathrm{A}1\stackrel{}{\to } \mathrm{A}1\mathrm{C}{1}_3 \\ \mathrm{d}.\mathrm{Fe}\stackrel{}{\to } {\mathrm{FeSO}}_4\stackrel{}{\to } \mathrm{Fe}{\left(\mathrm{OH}\right)}_2\stackrel{}{\to }\mathrm{Fe}{\left(\mathrm{OH}\right)}_3\stackrel{}{\to } \mathrm{FeC}{1}_3 \end{gathered}$$