Em tham khảo nha:

\(\begin{array}{l}
7)\\
{m_X} = \dfrac{{19,422 \times {{10}^{ - 23}}}}{3} = 6,474 \times {10^{ - 23}}(g)\\
{M_X} = \dfrac{{6,474 \times {{10}^{ - 23}}}}{{1,6605 \times {{10}^{ - 24}}}} \approx 39\,dvC \Rightarrow X:K\\
8)\\
{m_{{X_2}O}} = \dfrac{{31,208 \times {{10}^{ - 23}}}}{2} = 1,5604 \times {10^{ - 23}}(g)\\
{M_{{X_2}O}} = \dfrac{{1,5604 \times {{10}^{ - 23}}}}{{1,6605 \times {{10}^{ - 24}}}} \approx 94\,dvC\\
 \Rightarrow 2{M_X} + {M_O} = 94 \Rightarrow {M_X} = 39\,dvC\\
 \Rightarrow X:K\\
9)\\
{M_{{X_2}S{O_4}}} = \dfrac{{16,268 \times {{10}^{ - 23}}}}{{1,6605 \times {{10}^{ - 24}}}} \approx 98\,dvC\\
 \Rightarrow 2{M_X} + {M_S} + 4{M_O} = 98 \Rightarrow {M_X} = 1\,dvC\\
 \Rightarrow X:H\\
10)\\
{m_{X{{(HC{O_3})}_2}}} = \dfrac{{53,784 \times {{10}^{ - 23}}}}{2} = 2,6892 \times {10^{ - 22}}(g)\\
{M_{X{{(HC{O_3})}_2}}} = \dfrac{{2,6892 \times {{10}^{ - 22}}}}{{1,6605 \times {{10}^{ - 24}}}} \approx 162\,dvC\\
 \Rightarrow {M_X} + 2 \times ({M_H} + {M_C} + 3{M_O}) = 162 \Rightarrow {M_X} = 40\,dvC\\
 \Rightarrow X:Ca
\end{array}\)