a. Gọi CTHH là: \(\overset{\left(x\right)}{Fe}\overset{\left(II\right)}{SO_4}\)
Có: \(x.1=II.1\)
\(\Leftrightarrow x=II\)
Vậy .............
b. Gọi CTHH là: \(\overset{\left(y\right)}{N}\overset{\left(II\right)}{O_2}\)
Có: \(y.1=II.2\)
\(\Leftrightarrow y=IV\)
Vậy ............