NTKX = 2.12 = 24 (đvC)
Có 1 đvC = \(\dfrac{1}{12}.1,9926.10^{-23}=0,16605.10^{-23}\left(g\right)\)
=> \(NTK_X=24.0,16605.10^{-23}=3,9852.10^{-23}\left(g\right)\)
\(PTK_X=2.12=24\left(đvC\right)\)
\(\Rightarrow m_X=1,66.24=39,84\left(g\right)\)
\(\dfrac{M_X}{M_C}=2\Rightarrow M_X=2.12=24\left(DvC\right)\)
=> Vậy X là nguyên tử Magie
\(=>m_{Mg}=1,66.24=39,84\left(g\right)\)