Tổng số hạt trong phân tử MX là 84 hạt, trong đó s...

A

- Hướng dẫn giải

Phương pháp giải:

\(\left\{ \begin{gathered}
(2{p_M} + {n_M}) + (2{p_X} + {n_X}) = 84\,\,\,\,\,\,\,\,\,\,\,\,\,(1) \hfill \\
(2{p_M} + 2{p_X}) - (2{n_M} + {n_X}) = 28\,\,\,\,\,\,\,\,\,\,\,(2) \hfill \\
{n_M} - {n_X} = 12\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(3) \hfill \\
(2{p_M} + {n_M}) - (2{p_X} + {n_X}) = 36\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(4) \hfill \\
\end{gathered} \right.\)

Lấy (1)+(2)  => 4p_M+ 4p_X= 112  => p_M  +p_X = 28

Lấy 4)-(3)  => 2p_M- 2p_X = 24  => p_M-p_X = 12

=> p_M, p_X

Giải chi tiết:

\(\left\{ \begin{gathered}
(2{p_M} + {n_M}) + (2{p_X} + {n_X}) = 84\,\,\,\,\,\,\,\,\,\,\,\,\,(1) \hfill \\
(2{p_M} + 2{p_X}) - (2{n_M} + {n_X}) = 28\,\,\,\,\,\,\,\,\,\,\,(2) \hfill \\
{n_M} - {n_X} = 12\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(3) \hfill \\
(2{p_M} + {n_M}) - (2{p_X} + {n_X}) = 36\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(4) \hfill \\
\end{gathered} \right.\)

Lấy (1)+(2)  => 4p_M+ 4p_X= 112  => p_M  +p_X = 28

Lấy 4)-(3)  => 2p_M- 2p_X = 24  => p_M-p_X = 12

\(\left\{ \begin{gathered}
{p_{M\;}} + {p_X} = {\text{ }}28 \hfill \\
{p_{M\;}} - {p_X} = {\text{ 12}} \hfill \\
\end{gathered} \right. \to \left\{ \begin{gathered}
{p_M} = 20 \hfill \\
{p_X} = 8 \hfill \\
\end{gathered} \right.\)

=> MX: CaO

Đáp án A