Em tham khảo nha:

\(\begin{array}{l}
1)\\
{M_X} = 2{M_O} = 2 \times 16 = 32\,dvC\\
X: \text{ Lưu huỳnh,KHHH:  } S\\
2)\\
{M_X} = 3,5{M_O} = 3,5 \times 16 = 56dvC\\
 \Rightarrow X: \text{Sắt,KHHH:   }Fe\\
3)\\
3{M_X} = 4{M_{Mg}} \Rightarrow {M_X} = \dfrac{{4 \times 24}}{3} = 32dvC\\
X: \text{ Lưu huỳnh,KHHH:  }S\\
4)\\
19{M_X} = 11{M_F} \Rightarrow {M_X} = \dfrac{{11 \times 9}}{{19}} = 5,21\\
5)\\
3{M_X} = 8{M_C} \Rightarrow {M_X} = \dfrac{{8 \times 12}}{3} = 32\,dvC\\
X: \text{ Lưu huỳnh,KHHH:  }S\\
6)\\
3{M_X} = 16{M_C} \Rightarrow {M_X} = \dfrac{{16 \times 12}}{3} = 64\,dvC\\
X: \text{ Đồng ,KHHH:  }Cu\\
7)\\
{M_X} = {M_{Mg}} + {M_S} = 24 + 32 = 56\,dvC\\
 \Rightarrow X: \text{Sắt,KHHH:  }Fe
\end{array}\)