a) ta có CTHH: \(Cu^I_xO_y^{II}\)
\(\rightarrow I.x=II.y\rightarrow\dfrac{x}{y}=\dfrac{II}{I}=\dfrac{2}{1}\rightarrow\left[{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
\(\rightarrow CTHH:Cu_2O\)
b) ta có CTHH: \(Ca^{II}_x\left(NO_3\right)^I_y\)
\(\rightarrow II.x=I.y\rightarrow\dfrac{x}{y}=\dfrac{I}{II}=\dfrac{1}{2}\rightarrow\left[{}\begin{matrix}x=1\\y=2\end{matrix}\right.\)
\(\rightarrow CTHH:Ca\left(NO_3\right)_2\)